We are upgrading our CICS. We will need both versions for awhile until full upgrade is complete.
What would be the best way to go about doing this within Alchemist?
Would it be to define new entity types for our online models?
The best approach would be to accommodate the different CICS versions within your PCL (Process Control Language) and not touch the actual entity types.
Depending upon how this is to be implemented you could use one of the request or entity variables (such as one of the description lines) to determine which of the two versions to use. The PCL would then test this variable to use the appropriate version. Then later when you are back to only one version, modify the PCL again to contain only the one version.
It would also be simpler to enforce one particular version of CICS per change request in which case it would be best to use a request variable (description line) for identification.
With this PCL approach, you can leave your ETD untouched which should ensure no impact to cross-reference.
You should avoid using any of the management fields for this CICS version purpose since these are used for locking, masking, etc.