Purpose of INDEX file

[Gerard Seibert]

I know that 'portupgrade' uses the INDEX file. What I am not sure of, is 
if I need the file if I am not using 'portupgrade'. I use 'portmanager' 
which claims it does not require the INDEX file. If I do not need it, then 
I assume it is safe to not bother building it or fetching one.

Does the INDEX file serve any other purpose?

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Thanks!

Gerard Seibert
gerard-seibert at suscom.net