First defined in: FKiSS3
The letfix action sets the value of variable to the fix
value of target.
variable
variable must be a variable name.
target
In FKiSS3, target must be an object number.
In FKiSS4, target may be an object number or a variable
representing an object number.
Example:
;@ letfix(F, #5) ; Get the fix value of object #5 and put it in variable F.
;@ letfix(F, VarObj) ; Get the fix value of the object identified by VarObj and put it in F.