Tag-Length-Value encoding is a method of data encoding, governed by the rules of ASN.1-BER (per Annex B, Book 3, of the EMV 4.3 specifications). 

See this Wikipedia article 

https://en.wikipedia.org/wiki/Type-length-value

See also:

• Page:
  TLV parser in c
• Page:
  EMV tag search results
• Page:
  Terminal verification results - Wikipedia
• Page:
  How to Parse TLVs in JavaScript
• Page:
  Complete list of EMV & NFC tags
• PDF File
  Downloads - Home > 80000503-001 ID TECH TLV Tag Reference Guide.pdf
• Page:
  Why aren't tags 57 and 5A returned with my EMV transaction?
• Page:
  9F1E - EMV Tag: Interface Device (IFD) Serial Number
• Page:
  How can I get, find and retrieve EMV Tags?
• Page:
  DFEF7D - ID TECH Tag: Number of reinsert after a bad insert
• Page:
  TLV Decoder
• PDF File
  Downloads - Home > Tech Note 011 -- Tags for Obtaining Encrypted Track Data.pdf
• Page:
  Parsomatic
• Page:
  Parsomatic. How to parse TLVs? How to parse transaction data (EMV, MSR or MSD)?
• Page:
  TLV Utilities