Specifications¶

An ISO8583 spec is a Python dict instance. It describes how each field needs to be encoded or decoded.

Fields¶

Supported fields:

h - Message Header. If a specification does not have a header then set max_len to 0 to disable it.
t - Message Type Identifier
p - Primary Bitmap
1 - Secondary Bitmap
2 .. 128 - Regular fields

Field Properties¶

Each field defines these properties:

data_enc - field’s data encoding type, where:
- Use b for binary-coded decimal data (e.g. an ABCD hex string is encoded as \xAB\xCD 2-byte value).
- Otherwise, provide any valid Python encoding. For example, ascii or latin-1 for ASCII data and cp500 or similar for EBCDIC data.
len_enc - field’s length encoding type. Follows the same rules as data_enc. Some fields, such as ICC data, could have binary data but ASCII length. This parameter does not affect fixed-length fields.
len_type - field’s length type: fixed, LVAR, LLVAR, etc. Expressed as number of bytes in field length. For example, ASCII LLVAR length takes up 2 bytes (b'00' - b'99'). BCD LLVAR length can take up only 1 byte (b'\x00' - b'\x63'). len_type depends on the type of len_enc being used. BCD len_enc can fit higher length ranges in fewer bytes.

len_type len_enc

ASCII / EBCDIC Binary-Coded Decimal

Fixed 0 0

LVAR 1 1

LLVAR 2 1

LLLVAR 3 2

LLLLVAR 4 2
max_len - field’s maximum length in bytes. For fixed fields max_len defines the fixed length of the field.
desc - field’s description that’s printed in a pretty format. desc plays no role in encoding or decoding data. It’s safe to omit it from the specifications. If omitted iso8583.pp() may or may not work as expected.

Sample Field Specifications¶

Binary-coded decimal primary bitmap (the same applies to the secondary bitmap):

specification["p"] = {
    "data_enc": "b",
    "len_enc": "b",
    "len_type": 0,
    "max_len": 8,
    "desc": "BCD bitmap, e.g. \x12\x34\x56\x78\x90\xAB\xCD\xEF"
}

Hex string primary bitmap (the same applies to the secondary bitmap):

specification["p"] = {
    "data_enc": "ascii",
    "len_enc": "ascii",
    "len_type": 0,
    "max_len": 16,
    "desc": "Hex string bitmap, e.g 1234567890ABCDEF"
}

Field 2 that is a BCD fixed length field of 10 bytes:

specification["2"] = {
    "data_enc": "b",
    "len_enc": "b",
    "len_type": 0,
    "max_len": 10,
    "desc": "BCD fixed field"
}

Field 3 that is an ASCII LLVAR field of maximum 20 bytes:

specification["3"] = {
    "data_enc": "ascii",
    "len_enc": "ascii",
    "len_type": 2,
    "max_len": 20,
    "desc": "ASCII LLVAR field"
}

Field 4 that is an EBCDIC LLLVAR field of maximum 150 bytes:

specification["4"] = {
    "data_enc": "cp500",
    "len_enc": "cp500",
    "len_type": 3,
    "max_len": 150,
    "desc": "EBCDIC LLLVAR field"
}

Sample Message Specifications¶

ASCII/BCD¶

Bitmaps, MACs, PIN, and ICC data are in BCD:

default = {
"h":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 0,   "desc": "Message Header"},
"t":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Type"},
"p":   {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Bitmap, Primary"},
"1":   {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Bitmap, Secondary"},
"2":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 19,  "desc": "Primary Account Number (PAN)"},
"3":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Processing Code"},
"4":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Transaction"},
"5":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Settlement"},
"6":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Cardholder Billing"},
"7":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transmission Date and Time"},
"8":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Amount, Cardholder Billing Fee"},
"9":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Conversion Rate, Settlement"},
"10":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Conversion Rate, Cardholder Billing"},
"11":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "System Trace Audit Number"},
"12":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Time, Local Transaction"},
"13":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Local Transaction"},
"14":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Expiration"},
"15":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Settlement"},
"16":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Conversion"},
"17":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Capture"},
"18":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Merchant Type"},
"19":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Acquiring Institution Country Code"},
"20":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "PAN Country Code"},
"21":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Forwarding Institution Country Code"},
"22":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Point-of-Service Entry Mode"},
"23":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "PAN Sequence Number"},
"24":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Network International ID (NII)"},
"25":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Point-of-Service Condition Code"},
"26":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Point-of-Service Capture Code"},
"27":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "Authorizing ID Response Length"},
"28":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Transaction Fee"},
"29":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Settlement Fee"},
"30":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Transaction Processing Fee"},
"31":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Settlement Processing Fee"},
"32":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Acquiring Institution ID Code"},
"33":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Forwarding Institution ID Code"},
"34":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Primary Account Number, Extended"},
"35":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 37,  "desc": "Track 2 Data"},
"36":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 104, "desc": "Track 3 Data"},
"37":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Retrieval Reference Number"},
"38":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Authorization ID Response"},
"39":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Response Code"},
"40":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Service Restriction Code"},
"41":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Card Acceptor Terminal ID"},
"42":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 15,  "desc": "Card Acceptor ID Code"},
"43":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 40,  "desc": "Card Acceptor Name/Location"},
"44":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 25,  "desc": "Additional Response Data"},
"45":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 76,  "desc": "Track 1 Data"},
"46":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - ISO"},
"47":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - National"},
"48":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - Private"},
"49":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Transaction"},
"50":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Settlement"},
"51":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Cardholder Billing"},
"52":  {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "PIN"},
"53":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Security-Related Control Information"},
"54":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 240, "desc": "Additional Amounts"},
"55":  {"data_enc": "b",     "len_enc": "ascii", "len_type": 3, "max_len": 255, "desc": "ICC data"},
"56":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved ISO"},
"57":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"58":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"59":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"60":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"61":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved Private"},
"62":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved Private"},
"63":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved Private"},
"64":  {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "MAC"},
"65":  {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Bitmap, Extended"},
"66":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "Settlement Code"},
"67":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Extended Payment Code"},
"68":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Receiving Institution Country Code"},
"69":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Settlement Institution Country Code"},
"70":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Network Management Information Code"},
"71":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Number"},
"72":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Number, Last"},
"73":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Date, Action"},
"74":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Credits, Number"},
"75":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Credits, Reversal Number"},
"76":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Debits, Number"},
"77":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Debits, Reversal Number"},
"78":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transfer, Number"},
"79":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transfer, Reversal Number"},
"80":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Inquiries, Number"},
"81":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Authorizations, Number"},
"82":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Credits, Processing Fee Amount"},
"83":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Credits, Transaction Fee Amount"},
"84":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Debits, Processing Fee Amount"},
"85":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Debits, Transaction Fee Amount"},
"86":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Credits, Amount"},
"87":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Credits, Reversal Amount"},
"88":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Debits, Amount"},
"89":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Debits, Reversal Amount"},
"90":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 42,  "desc": "Original Data Elements"},
"91":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "File Update Code"},
"92":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "File Security Code"},
"93":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 5,   "desc": "Response Indicator"},
"94":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 7,   "desc": "Service Indicator"},
"95":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 42,  "desc": "Replacement Amounts"},
"96":  {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Message Security Code"},
"97":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 17,  "desc": "Amount, Net Settlement"},
"98":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 25,  "desc": "Payee"},
"99":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Settlement Institution ID Code"},
"100": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Receiving Institution ID Code"},
"101": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 17,  "desc": "File Name"},
"102": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Account ID 1"},
"103": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Account ID 2"},
"104": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 100, "desc": "Transaction Description"},
"105": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"106": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"107": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"108": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"109": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"110": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"111": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"112": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"113": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"114": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"115": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"116": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"117": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"118": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"119": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"120": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"121": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"122": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"123": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"124": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"125": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"126": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"127": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"128": {"data_enc": "b",     "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "MAC"}
}

ASCII¶

All fields are in ASCII:

default_ascii = {
"h":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 0,   "desc": "Message Header"},
"t":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Type"},
"p":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Bitmap, Primary"},
"1":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Bitmap, Secondary"},
"2":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 19,  "desc": "Primary Account Number (PAN)"},
"3":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Processing Code"},
"4":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Transaction"},
"5":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Settlement"},
"6":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Cardholder Billing"},
"7":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transmission Date and Time"},
"8":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Amount, Cardholder Billing Fee"},
"9":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Conversion Rate, Settlement"},
"10":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Conversion Rate, Cardholder Billing"},
"11":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "System Trace Audit Number"},
"12":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Time, Local Transaction"},
"13":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Local Transaction"},
"14":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Expiration"},
"15":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Settlement"},
"16":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Conversion"},
"17":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Capture"},
"18":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Merchant Type"},
"19":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Acquiring Institution Country Code"},
"20":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "PAN Country Code"},
"21":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Forwarding Institution Country Code"},
"22":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Point-of-Service Entry Mode"},
"23":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "PAN Sequence Number"},
"24":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Network International ID (NII)"},
"25":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Point-of-Service Condition Code"},
"26":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Point-of-Service Capture Code"},
"27":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "Authorizing ID Response Length"},
"28":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Transaction Fee"},
"29":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Settlement Fee"},
"30":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Transaction Processing Fee"},
"31":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Settlement Processing Fee"},
"32":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Acquiring Institution ID Code"},
"33":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Forwarding Institution ID Code"},
"34":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Primary Account Number, Extended"},
"35":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 37,  "desc": "Track 2 Data"},
"36":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 104, "desc": "Track 3 Data"},
"37":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Retrieval Reference Number"},
"38":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Authorization ID Response"},
"39":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Response Code"},
"40":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Service Restriction Code"},
"41":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Card Acceptor Terminal ID"},
"42":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 15,  "desc": "Card Acceptor ID Code"},
"43":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 40,  "desc": "Card Acceptor Name/Location"},
"44":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 25,  "desc": "Additional Response Data"},
"45":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 76,  "desc": "Track 1 Data"},
"46":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - ISO"},
"47":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - National"},
"48":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - Private"},
"49":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Transaction"},
"50":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Settlement"},
"51":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Cardholder Billing"},
"52":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "PIN"},
"53":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Security-Related Control Information"},
"54":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 240, "desc": "Additional Amounts"},
"55":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 510, "desc": "ICC data"},
"56":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved ISO"},
"57":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"58":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"59":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"60":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"61":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved Private"},
"62":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved Private"},
"63":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved Private"},
"64":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "MAC"},
"65":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Bitmap, Extended"},
"66":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "Settlement Code"},
"67":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Extended Payment Code"},
"68":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Receiving Institution Country Code"},
"69":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Settlement Institution Country Code"},
"70":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Network Management Information Code"},
"71":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Number"},
"72":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Number, Last"},
"73":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Date, Action"},
"74":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Credits, Number"},
"75":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Credits, Reversal Number"},
"76":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Debits, Number"},
"77":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Debits, Reversal Number"},
"78":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transfer, Number"},
"79":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transfer, Reversal Number"},
"80":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Inquiries, Number"},
"81":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Authorizations, Number"},
"82":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Credits, Processing Fee Amount"},
"83":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Credits, Transaction Fee Amount"},
"84":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Debits, Processing Fee Amount"},
"85":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Debits, Transaction Fee Amount"},
"86":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Credits, Amount"},
"87":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Credits, Reversal Amount"},
"88":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Debits, Amount"},
"89":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Debits, Reversal Amount"},
"90":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 42,  "desc": "Original Data Elements"},
"91":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "File Update Code"},
"92":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "File Security Code"},
"93":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 5,   "desc": "Response Indicator"},
"94":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 7,   "desc": "Service Indicator"},
"95":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 42,  "desc": "Replacement Amounts"},
"96":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Message Security Code"},
"97":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 17,  "desc": "Amount, Net Settlement"},
"98":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 25,  "desc": "Payee"},
"99":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Settlement Institution ID Code"},
"100": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Receiving Institution ID Code"},
"101": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 17,  "desc": "File Name"},
"102": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Account ID 1"},
"103": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Account ID 2"},
"104": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 100, "desc": "Transaction Description"},
"105": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"106": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"107": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"108": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"109": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"110": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"111": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for ISO Use"},
"112": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"113": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"114": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"115": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"116": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"117": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"118": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"119": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"120": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"121": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"122": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"123": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"124": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"125": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"126": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"127": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"128": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "MAC"}
}

len_type	len_enc
len_type	ASCII / EBCDIC	Binary-Coded Decimal
Fixed	`0`	`0`
LVAR	`1`	`1`
LLVAR	`2`	`1`
LLLVAR	`3`	`2`
LLLLVAR	`4`	`2`