There is only one file type that uses the .TEC extension:
TECkit Compiled Mapping File
A TEC file is a file created by TECkit (Text Encoding Conversion toolkit), a program used for conducting text conversions. It contains binary code that describes the mapping between a byte encoding and Unicode and vice versa. TEC files are sometimes used in conjunction with LaTeX technologies to convert characters on the fly when generating LaTeX documents in different languages.
You most likely will only encounter TEC files if you use TECkit for converting text between 8-bit and Unicode encodings. TEC files are compiled from source .MAP files, which include mappings between a byte encoding and Unicode in plain text.
TEC files can be compiled from MAP files using the Windows command-line compiler included with TECkit (TECkit_Compile.exe). Here is a sample command that compiles an example.map file:
C:\TECkit\>teckit_compile example.map -o example.tec
NOTE: TECkit was originally created to convert text from older 8-bit encodings to Unicode.
Updated: October 13, 2019