The ClearCase SCM adapter applies a hidden time rule to all config specs entered. This stops us from checking out files in a ClearCase branch, when trying ClearCase protests:

cleartool: Error: Element already has a branch of type "xyz" ("\main\xyz").
cleartool: Error: Unable to create branch requested by -mkbranch option in config spec.
cleartool: Error: Unable to check out "foo.c".

This is due to the fact that the ClearCase view isn't allowed to show something created after the starting time of the build due to the hidden time rule. This is in general a good thing when doing synchronized builds but in this case it is very troublesome. For example:

time mmm
element * CHECKEDOUT
element /myvob/... .../xyz/LATEST # Note that this LATEST rule has an implied rule "-time mmm" applied
element /myvob/... REL1 -mkbranch xyz
element /myvob/... /main/0 -mkbranch xyz
end time

Since the LATEST rule really points to a time before the checkout, the branch created by the checkout is not visible, hence ClearCase tries to create the branch twice causing an error.

We need rules which are exempted from the time directive, this would allow us to branch and modify files under source control during the build even in this QB releases. Typically, only files which are subject to change during the build should be exempted from the time rule. One crude way would be to make it possible to switch off the time rule all together (for non-synchronized builds). A suggested approach for synchronized builds would be to instead append the time rule to individual LATEST lines in the config spec, the ones not already having a time rule but only the ones having a -nocheckout option as the ones without that rule may be modified in the build; this would also make the change backward-compatible with how QB works today.