value = io.qry(func [, token, token2]); stat = io.qst();
%b/manif/iotable ... /* Process all device SCT's in the system */ sct = io.qry(_FFSDV); /* Get 1st SCT in system */ do { /* process that device */ ... sct = io.qry(_FNSDV, sct); /* Get next SCT */ } while (0 != io.qst()); /* Until we get a false */
IO.QST is used to retrieve the status from an immediately preceeding call to IO.QRY. Except for a possible call to .NULL() to retrieve the high order 36 bits of a 72 bit call to IO.QRY, there must be no intervening function calls.
Most calls to IO.QRY do not need a status check. If the call returns, it was successful. There are a few calls such as "convert device name", or "get next SCT" where the system returns a status in the indicator register. IO.QST is used to obtain an interpreted version of the status in the zero and negative indicators.
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