error(5) plan9 man page | unix.com

ERROR(5)							File Formats Manual							  ERROR(5)

NAME
       error - return an error

SYNOPSIS
       Rerror tag[2] ename[64]

DESCRIPTION
       The  Rerror  request (there is no Terror) is used to return an error string, of length 64 (ERRLEN in <libc.h>), describing the failure of a
       transaction.  It replaces the corresponding reply message that would accompany a successful call; its tag is that of the request.

																	  ERROR(5)