/usr/share/man/man3/Tcl_IsStandardChannel.3tcl.gz is in tcl8.4-doc 8.4.20-8.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man3/Tcl_OpenFileChannel.3tcl.gz
/usr/share/man/man3/Tcl_OpenFileChannel.3tcl.gz