delete - main stack vs substack

[jim sims]

Delete will purge a main stack from memory BUT will permanently delete  
a substack (like gone forever).

  I do not want to permanently delete a substack by mistake in an all- 
purpose handler I am writing, would the following be enough to make  
sure a stack is NOT a substack?

if stack tStackInQuestion is in the mainStacks then delete stack  
tStackInQuestion


sims