Prototype question

List,

Situation:
As I write new or modify old programs I am converting old PList entries
to prototypes.
We have hundreds of 'called' programs that have an identical set of
PList entries.

In our '/Copy' prototype source member, I have created a 'generic'
prototype to use for calling these programs:
D CalPgm          Pr                  ExtPgm(Called)
D  Pa           128A
D  Prm1 256A
D  Prm2 256A

I fill 'Called' with program name, do 'CalPgm (Pa:Prm1:Prm2);'
This method works fine for calling any of these programs. 

Problem:
I am writing a new program, the first that does not need to call any of
the old 'Plist' programs, so the field 'Called' was not declared.
I '/Copy'd the prototype source member into this new program for calling
some other programs prototyped there.

The program did not compile until I declared 'Called', either in the
calling program or in the prototype source.

I have three questions:

1. Since I am not 'using' this field (I am not using 'CalPgm'), why does
it need to be declared?

2. If others of you have run into this or similar situations, have you
found it better to declare the field(s) in the prototype source,
in the source of all programs that have the prototype source /Copy'd
into them whether the field is used or not,
have multiple prototype source members to copy in, or something else?
I want to pick the one that has the least negative repercussions.

3. Is it common to have declare fields in the 'prototype source member',
and if so, what other, if any, issues does this create?

(I started out thinking I would have one 'prototype' source member for
'all' prototyed programs, that would have 'only' prototypes in it,
and didn't consider doing any declarations there.)

TIA

Tim Kredlo