Merging from HEAD to branch

[Jesus M. Salvo Jr.]

1) Created a branch. changes were being committed on the branch.
2) At the same time, changes were being committed on the main tree ( HEAD ).
3) Merged the changes from the main tree to branch and then committed 
the merge on the branch. The main tree was tagged ( called 
mergedtobranch_ 20030117 ) so that I know at what point in the main tree 
were changes applied to the branch. The branch was also tagged after the 
merge-commit ( called mergedfrombranch_20030117 ).


My problem now is how to continually merge changes from the main tree to 
the branch after the initial merge
Which one is the correct command?

Retrieve the branch ( cvs update -r branchname )

and then one of

cvs -z9 update -P -d -jmergedtobranch_20030117 -jbranchname
cvs -z9 update -P -d -jmergedfrombranch_20030117 -jbranchname
cvs -z9 update -P -d -jHEAD
cvs -z9 update -P -d -jHEAD -jbranchname
cvs -z9 update -P -d -jmergedtobranch_20030117 -jHEAD