CMDVariables = yes | NO
TCC allows you to specify variables with only a single leading %; CMD requires both a leading and a trailing %. Normally TCC is able to detect this, but if you have variable names with embedded whitespace (a bad idea!) TCC will not expand the variable.
If you need as close to 100% CMD compatibility as possible, and you don't care about running existing TCC batch files or aliases, setting CMDVariables=yes will allow TCC to properly expand these types of variable names.