sort first field start with "ROM"

Hello!

I have the following file when I grep just for "ROM" i get everything but
I am looking for line start with "ROM" only in the first field only, where "ROM" is the first 3 characters.

Thanks,

ROMMANC ROM-MPI
ROMMAND ROM-rty
ROMMANE ROM-Mii
ROMMANF RON-poi
MAAROMP ROS-MPI
MSTROMP ROM-MPI

So the out put should be:

ROMMANC
ROMMAND
ROMMANE
ROMMANF

Anchor the search to the beginning of the line:

grep ^ROM FILENAME

Thank you very much, that was easy but did not thought about it.