Character values see in numeric variable

[Sanjay_M]

When I open a SAS dataset, there is a numeric variable (var1) which shows character values  like C, M when opened

Also,

There is a code that queries that dataset and that numeric variable var1 as below

data test;

    set myds;

    if var1 = .C then newvar=10;

run;

Proc contents show that there is no format applied on that column. That variable var1 is num 8.

What does this .C mean and why are character variables shown in a numeric field?

[PeterClemmensen]

Please see the code below. SAS interprets .C, .A and such as missing values. However, they are missing as PROC FREQ reveals.

data test;
    a=.A;output;
    a=.;output;
    a=.B;output;
run;

data test2;
    set test;
    if a=.B then dummy=1;
    else dummy=0;
run;

proc freq data=test;
run;

[Sanjay_M]

Thanks for the quick response.

Is this a feature? why will we need Character missing values?

It is pretty confusing

[Tom · Accepted solution]

In addition to the normal missing value SAS supports 27 special missing values which you represent in code as ._, .A, .b,  up to  .z.

You can use them to make different categories of missing values.  For example if you had a survey question you might use one to mean question not asked, another to mean respondent refused to answer, another to mean respondent doesn't know the answer, etc.