Recording approximate dates

[calberga]

I don't know if this is the place for this question, if not, kindly direct me to the correct sub-forum.

I am working with scanned photographs.  Some have exact dates (usually scribbled on the back), others have notes such as "late 30s", or "around 1953", still others can be guessed by the age of individuals, but usually only within a few years, depending on the approximate date.

Are there any conventions for recording such information that can be sorted in a reasonable way? 

[Phil Harvey]

The only way to do this is with partial dates.  See FAQ number 5 for details about how this is done with XMP date/time tags.  With EXIF, partial date/time values are also possible by filling the appropriate field with spaces (you must use the -n option when writing with ExifTool if you want to do this).

- Phil