DECRQCRA—Request Checksum of Rectangular Area
This control function requests a checksum of the specified rectangular area in the specified page. The terminal returns a checksum report (DECCKSR) in response to this request.
3/n . . . 3/n
is a numeric label you can provide to identify the checksum request. The checksum report returns this number. The number serves to differentiate between multiple checksum reports.
is the page number that has the rectangular area. If Pp is 0 or omitted, then the terminal ignores the following parameters and reports a checksum for all pages in page memory. If Pp is a higher number than the number of pages available, then the terminal reports on the last page.
are the top, left, bottom, and right borders of the rectangular area. Pt and Pb are line numbers. Pt must be less than or equal to Pb. Pl and Pr are column numbers. Pl must be less than or equal to Pr.
Defaults are Pt = 1, Pb = current page length, Pr = current page width. If these parameters are omitted, then the terminal returns a checksum of page Pp.
Note on DECRQCRA
The coordinates of the rectangular area are affected by the setting of origin mode (DECOM).