[Vince]

It's a tag override. It basically removes the tag of a variable if it has one. This is mostly used to get rid "argument type mismatch" warnings when variables with non-standard tags (e.g. Text:, Db_result:, ...) are passed to functions like format or CallLocalFunction.

If you look up the definition of those two functions you will notice that it has a parameter:

Код:

{Float,_}:...

This means that it accepts variables that are either Float or have no tag. Trying to pass any of the types mentioned above will result in a warning.