Hi,
TLV stands for Type (Length Value), not Tag. TLVs are widely used in many option headers, but there's no generic TLC implementation as far as I know, also because it's kinda pointless.
Anyway, they're extremely easy to develop, so I don't really think you'd learn much from them. The basis is "read 1 byte, read another byte, read x more bytes according to what's in the 2nd byte", with some minor differences.
T.