Checksums allow component files to be validated and repaired using ⎕FCHK.

From Version 13.1 onwards, components which contain checksums are also validated on every component read.

Although not recommended, applications which favour performance over security may disable checksum validation by ⎕FREAD using this function.

Y is an integer defined as follows:

Value	Description
0	⎕FREAD will not validate checksums.
1	⎕FREAD will validate checksums when they are present. This is the default.

The shy result R is the previous value of this setting.