CTLOP_SVA (opcodes 6 and 7) are normally only used internally by A-Shell, in conjunction with command which save and restore full or partial screen areas (e.g. TCRTs 148, 149, 202, 203, plus pop-up subroutines like MSBOXX, INMEMO, etc.) If for some reason you wanted to do this directly, note the following:

•   You must specify up through the ecol parameter.

•   The func parameter should be set to the string representation of a numeric ID (e.g. "1"). The same ID must be specified on the restore operation as for the save (this is how the correct set of saved controls is located.)