Is ccsid 65535 cvt to 37 painless?

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I have a customer V4r5 with default ccsid 65535, using
ftp, CA transfers, async credit card comm using qascii code page
conversion. Now need to add web cgi. The cgidev2 docs
strongly suggest changing system to a proper ccsid, and
is "usually" is painless. I don't have a spare system to test
that theory.
Is it truly required? Is it safe?
I searched the archives and found lots of discussion about ccsid, but
not really desribing how the change went (if they did it at all).
Sorry for the post to two lists, but question equally applies.

jim franz (who will be shot if i bring the applications down)

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