AATCC and ASTM standards are named so that they have the year of publication at the end of their number:
This means it was published in 2013, not that there are 13 different parts to the standard.
A number in brackets refers to the year that the standard was re-approved.
Any deviations from the standard will usually be referred to as options, parts or sections:
For ISO standards, the number following the dash indicates a part to the standard, with the year of publication being at the end.
If a standard is quoted without a year, it is taken as being the current standard.
The year of publication can be found within the document, usually with a short history about the standard.
A PDF version of this FAQ is available for reference.