Depending on the format type, different record fields are used
for output and input. The variable x stands for the
written or read value.
%f):%i):MASK==0 (because NOBT is not set):x=RVALRAL=x, VAL=RVAL>>SHFTMASK!=0:x=RVAL&MASKRBV=RVAL=x&MASK, VAL=RVAL>>SHFTMASK is initialized to NOBT 1-bits shifted
left by SHFT (((2^NOBT)-1)<<SHFT).
The record calculates RVAL=VAL<<SHFT.
%s):
During initialization, the @init handler is executed, if
present.