Unfortunately, ZIP_CODE could include zip+4 (character data, length up to 10), if the field length is greater than 5 (and any input validation allows it). And, so, it would be a gamble if/when you attempt to use PROC IMPORT and the first "GUESSINGROWS" values are all five-digit and then comes a zip+4 which would be invalid and the result would be a SAS MISSING value. As well, consider inclusion of other mail/postal codes which may occur any in an input file -- alpha-numeric strings, imbedded blanks likely.
Interesting challenge to consider when using smart tools/wizards for a manually-defined DATA step substitution.
Scott Barry
SBBWorks, Inc.