View Gives Different (Better?) Result

This is a little strange.

data class;
set sashelp.class;
keep name nosuch;
retain nosuch;
run;

As expected, the log shows:

NOTE: Variable nosuch is uninitialized.

then

WARNING: The variable nosuch in the DROP, KEEP, or
RENAME list has never been referenced.

NOTE: The data set WORK.CLASS has 19 observations and 1 variables.

*not* as expected. Usually, variables are included in the PDV even if not
initialized. Not in this situation.

Moreover, a view behaves differently. Make it:

data classview / view=classview;
set sashelp.class;
keep name nosuch;
retain nosuch;
run;

to define the view, then

data classfromview;
set classview;
run;

to evaluate it, and the log shows:

NOTE: Variable nosuch is uninitialized.

and

NOTE: The data set WORK.CLASSFROMVIEW has 19 observations
and 2 variables.

So in this case the uninitialized variable *is* created.

So there are two questions:

1. Why is the variable NOSUCH not present in the first data set created?

2. Why does a view behave differently in this regard?

 

Case 1.

A retained variable that is neither assigned a value nor type&length (by
direct statement {such as VAR=..., retain VAR value, LENGTH, ATTRIB or array
initialization} or indirect action {such as a SET or PUT})does not enter
the PDV.
[ I recall a thread on this a few years back. ]

The compiler never encounters Nosuch in a situation wherein default
attributes type/length are necessary to be known during data step
compilation. This state means Nosuch does not enter the PDV.

Case 2.

The same data step, but as a view

This one is perplexing.
Nosuch takes default attributes of type numeric and length 8.


Case 1 examples: statements indirectly cause compiler to enter Nosuch into
PDV
-----------------
data class;
set sashelp.class;
keep name nosuch;
retain nosuch;
put nosuch=;
run;
-----------------
data class;
set sashelp.class;
keep name nosuch;
retain nosuch;
a = addr (nosuch);
run;