IS REQUESTED statement

Question

Hi experts,
I would like to know, how is "IS REQUESTED" statement working
The ABAP documentation says:
"The logical expression checks whether an output parameter para of a procedure is requested. The expression is true if at the call an actual parameter was assigned to the formal parameter.
This logical expression is possible only in function modules and methods. "
Is it mean, that If I look at on the function call, then it is determined or not as an export, import parameter?? Maybe I'm wrong, so that's why I'm asking.

Answer 1

in the function modules you have import/export/tables etc to be passed or to fetched.
the parameter here has two options : option or not . (u can find that as a check bod in the import/export... tabs in FMs)
if its a optional export parameter,then it may be asked while calling the SF or might not be.
so when a option parameter value is needed that mean FM call has passed some field to it to get the data, then this IS REQUESTED option comes to action. hope you get my point,.
lets say FM XYZ has following things in definition.
import (this u pass from program)
abcd type c optional
defg type  c
export(this you request from program)
lmn type string
opqr type string optional.
and your program FM call is:
call function 'XYZ'
exporting
*abcd =     --> no need to pass as its optional
defg = '123'
importing
lmn = lv_lmn
opqr = lv_pqr ---> this is optional . u may or may not pass.
so from in the FM source code this can be written.
if opqr IS REQUESTED.
    opqr = 'hi there'.
endif.
and you get the value in lv_pqr.
hope you understand my point,
thank you
Somu