Log:

16   data work.homework;
17   input name $ age height;
18   infile 'file-specification';
19   if age LE 10;
20   

NOTE: Invalid data for age in line 21 6-14.
RULE:      ----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9-
21         John McCloskey 35 71
name=John age=. height=35 _ERROR_=1 _N_=1
NOTE: Invalid data for age in line 22 6-14.
22         June Rosesette 10 43
name=June age=. height=10 _ERROR_=1 _N_=2
NOTE: Invalid data for age in line 23 8-12.
23         Tineke Jones 9 37
name=Tineke age=. height=9 _ERROR_=1 _N_=3
NOTE: The data set WORK.HOMEWORK has 3 observations and 3 variables.
NOTE: DATA statement used (Total process time):
      real time           0.03 seconds
      cpu time            0.01 seconds


24   ;
25   run;

Commentary:
The list Input method used to read file variables name, age and height will be read by SAS in order with a space as the delimiter in this case. The variable age is of numeric type so SAS will try to read a string for this variable and assign a missing value (see the log above). In SAS, a missing value is always less than any numeric value, so the statement if age LE 10; will be true for each processed record and a record will be written to the output.

Data Set(s):