defval ??

[John Papineau]

Greetings GRADS warriors-

1)   I am attempting to write a script using 'defval'.
Specifically, I want to _retrieve a value like U wind_  (ugrdprs in
my nomenclature) at a point. If I run:

'q defval ugrdprs 'i' 'j

the following error message results:

 "defined name not found"
I
 have tried all possible combinations of  ' around the variables, etc
Have also tried specific grid values like 'q defval ugrdprs '30' '25
same error message.

2) It is unclear from the documentation if I have ## number of files
(each at a
different time) that I want to query for specific values, such as noted
above, do I need to use the "read" command? or just have them all open?

3)  What does "rc" stand for?  record code, if so what does it mean?

Many thanks- John