I don't understand "??" in INPUT statement

[SushilNayak]

Hi,
I was just going through an old code, saw this wierd ?? in the INPUT statement, can someone please tell me what this ?? does, i have searched on GOOGLE but ?? is pretty common string online so couldn't find anything.

DATA DUMMY;
INFILE PREVFILE;
INPUT @01 TESTBYTE ?? $CHAR1.;
RUN;

Thanks!

[GertNissen]

? or ??
The optional question mark (?) and double question mark (??) format modifiers suppress the printing of both the error messages and the input lines when invalid data values are read. The ? modifier suppresses the invalid data message. The ?? modifier also suppresses the invalid data message and, in addition, prevents the automatic variable _ERROR_ from being set to 1 when invalid data are read.

Found it in the SAS doc http://support.sas.com/onlinedoc/913/getDoc/da/lrdict.hlp/a000146292.htm#a000146295