What happens when SAS Detects a Data Error? What does get written to SAS log?

SAS log:

•a note that describes the error
•a list of values that are stored in the input buffer
•a list of values that are stored in the program data vector
Note that the values that are listed in the program data vector include two variables that are created automatically by SAS:

_N_
counts the number of times the DATA step iterates._ERROR_
indicates the occurrence of an error during an execution of the DATA step. The value that is assigned to the variable _ERROR_

is 0 when no error is encountered and 1 when an error is encountered.

These automatic variables are assigned temporarily to each observation, and are not stored with the data set.