I have a similar question so I thought I would tack it to the end of this thread.

DIM reply(i) AS STRING
CALL Answer(reply())
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SUB Answer(passedReply() AS STRING)
    PRINT passedReply(i)
END SUB

The above code works just fine ...

DIM reply(i) AS STRING
PRINT Answer(reply())
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.
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FUNCTION Answer(passedReply() AS STRING)
    Answer = passedReply(i)
END FUNCTION

This code produces IILEGAL STRING-NUMBER CONVERSION error

However, if 'DEFSTR A' is used, then the above function works fine. The function name needs to be defined as string.

Should FUNCTIONS and SUBS differ in this way? It took me some time to figure out why the FUNCTION wouldn't work.