Qualified data structure use

O Brilliant Ones:

I am at V5R2 and can't seem to find much information about where one can
and/or cannot use a fully qualified data structure field, except from
compile errors.

The manual says: "Fully qualified names are allowed in any free-form
calculation specifications"

and
SvCYMD = TvRtrvOP.TvRecd.TvCYMD;     is okay 
 and
Test(DE) *YMD TvRecd.TvCYMD;   is okay

 but
Test(DE) *YMD TvRtrvOP.TvRecd.TvCYMD;
 and (stuck parenthesis around as a WAG for solution) 
Test(DE) *YMD (TvRtrvOP.TvRecd.TvCYMD);
Both give the compile error "RNF0623 - The qualified name is not specified
correctly."

First of all, I don't understand why one shouldn't be able to use them
anywhere they "fit".
Secondly, if one can use a qualified name in a situation, why not a "fully"
qualified name in the same situation?

Any direction to pertinent resources would be greatly appreciated.

TIA

Tim Kredlo