(PHP 4 >= 4.0.7, PHP 5, PHP 7)
This function is
currently not documented; only its argument list is available.
A FrontBase link identifier
returned by fbsql_connect() or
If optional and not specified,
the function will try to find an open link to the FrontBase server and if no
such link is found it will try to create one as if
fbsql_connect() was called with no arguments.