@chimukah wrote: since the AEENDTC is U, i guess its unknown and it has to be missing.
Yes, that's probably best. As @Patrick points out, it's typically better to set a value to missing than to give a value that will produce invalid or misleading results. If you're not sure, the safest course is to set to missing.
The little program I showed you can be used as a sort of pattern or template for the parse-clean-check process, but you must determine what cleaning rules are appropriate for your situation and your data. My program is meant to illustrate a technique but by no means should you accept my sample rules unless they really fit your data.
Jim
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