The EMV tag data consists of a list of Tag Length Value (TLV) Tags in BER-TLV format. It is highly recommended to limit the tags sent in the EMV tag data field to those defined in the EMV Request Tags section.

There are three parts to a TLV tag.

[Tag][Value Length][Value] (ex. "9F4005F000F0A001")
where
Tag Name = 9F40
Value Length (in bytes) = 05 Value (Hex representation of bytes. Example, "F0" – 1-byte) = F000F0A001

Heartland only supports up to two-byte tags, thus TLV-BER rules for subsequent byte tag number continuation (bit-8 indicates continuation of tag name) do not apply. For example, FFC6 is a valid Heartland tag even though C6 results in bit-8 being set.

The length subfield may be one or more bytes.

• If bit 8 of the most significant byte is set to 0, the length subfield consists of 1 byte. Bits 7 to 1 code the number of bytes of the value subfield.
• If bit 8 of the most significant byte is set to 1, bits 7 to 1 code the number of subsequent bytes in the length subfield.

The subsequent bytes in the length subfield code an integer representing the number of bytes in the value subfield.

• EMV Request Tags
• EMV Response Tags