This command is part of the TclX pacakge.

funlock fileId ?start? ?length? ?origin?

Remove a lock from a file that was previously placed with the flock command. The arguments are the same as for the flock command, see that command for more details.

The funlock command is not available on Windows 95. It is available on Windows NT.

There is no funlock in Tcl...

... but there is in TclX.

... and there is the proposal tclx file commands for core