Template:T comment
Expression error: Unrecognized punctuation character "{".
Expression error: Unrecognized punctuation character "{".
Expression error: Unrecognized punctuation character "{".
Expression error: Unrecognized punctuation character "{".
Example
edit"{{t comment|4}}" gives "12
12
12
12
" [1]
"{{subst:t comment|4}}" gives "12
12
12
12
"
"{{subst:t comment|subst1=subst:|4}}" gives "Expression error: Unrecognised punctuation character "?"
12
12
12
"
"{{t comment|4|<!--multiply by 3-->=5|=6}}" gives "12
12
Expression error: Unexpected number.
138
"
"{{subst:t comment|4|<!--multiply by 3-->=5|=6}}" gives "12
12
12
12
"
Apparently comments in parameter names in parameter definitions are ignored, and on transclusion in parameter tags also, but not on substitution in parameter tags, so there cannot be a match.