TLVvelden

TLVvelden, or TLV fields, refers to the field-level components that constitute a Type-Length-Value encoded data element in many digital systems. The concept is common in data interchange formats and storage protocols where data elements are described by a tag, a length, and a value.

In a TLV-encoded unit, the Type (or Tag) identifies the kind of data or its semantic meaning, the Length field specifies how many bytes are in the Value, and the Value contains the actual data. Some implementations allow the Tag to be multi-byte and to indicate whether the value is primitive or a container for nested TLV fields.

Length encoding varies by standard. Some use a short form for small lengths, while others use long-form encoding for larger values; some legacy BER encodings even support indefinite lengths, though strict profiles such as DER require definite lengths.

TLV fields appear in a wide range of applications. They are central to ASN.1 encoding schemes (BER and DER), widely used in smart cards and payment systems (for example ISO 7816 and EMV), and are common in NFC tags and several network protocols that require compact, self-describing data blocks.

Because TLV fields can be nested, TLVvelden enable hierarchical data models and forward compatibility; new data types can be added by introducing new tags without altering existing data structures. Reading TLV data typically involves sequential parsing of Tag, Length, and Value until the end of the data block.