In Scott listings, the general rule for set listings that extend several years is -- when no year is given for a major catalog number stamp, the stamp was issued in the first year listed in the year range. Unfortunately, there is no consistent rule when it comes to minor catalog numbers. Bad Scott.
Therefore, #2130 was issued in 1985.
You can make no assumptions about #2130a, although for modern stamps it is usually safe to assume the minor catalog number was issued AFTER the major catalog number. There are many exceptions for older stamps, so do not use this as a general rule.
#2130a was issued on June 27, 1988. You can get this information by looking at the First Day Cover section of your Scott US Specialized.

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