YES, you need to have a header.
HEre is an example from an ascii file
created using v.out.ascii command:]
ORGANIZATION: ENRD, Ft. Lewis, WA
DIGIT DATE: 1987
DIGIT NAME: Teresa Hanen
MAP NAME: Training Areas
MAP DATE: 1987
MAP SCALE: 24000
OTHER INFO: based on USGS Quads
ZONE: 10
WEST EDGE: 514000
EAST EDGE: 549000
SOUTH EDGE: 5193000
NORTH EDGE: 5224000
MAP THRESH: 24
VERTI:
From grass-lists-owner@moon.cecer.army.mil Fri Jan 20 14:37:51 1995
From: DCERTAIN@obsnsrv1.bio.uoknor.edu
Sender: grass-lists-owner@moon.cecer.army.mil
Reply-To: grassu-list@moon.cecer.army.mil
To: grassu-list@max.cecer.army.mil
Date: Fri, 20 Jan 1995 11:02:32 -0600 CST
Subject: ascii conversion
Priority: normal
X-Mailer: Pegasus Mail/Windows (v1.21)
Content-Length: 278I have a question about converting an ascii file to the digital
format needed by GRASS. We have it complete and think
it needs a header, but whenever we use v.import it says it
can not read the header. Do we need the header, or what
should we do to get v.import to work?John