Where is files like "sin_wave.tlc", "gain.tlc" located?

I'm trying to explore some tlc files. As in "genmap.tlc", I found codes like:

%generatefile Gain "gain.tlc" ... %generatefile Sin "sin_wave.tlc"

Conceptually the codes specify which tlc file shall be used for generating code for corresponding block. However, I cannot find the files "gain.tlc" or "sin_wave.tlc" on my harddrive. Is there any other mechanism employed to redirect the code generation chain to other files? Thanks!