\NeedsTeXFormat ¶Synopsis:
\NeedsTeXFormat{format}[format-date]
Specifies the format that this class must be run under. Often issued
as the first line of a class file, and most often used as:
\NeedsTeXFormat{LaTeX2e}. When a document using that class
is processed, the format being run must exactly match the format
name given, including case. If it does not match then execution stops
with an error like ‘This file needs format `LaTeX2e' but this is
`plain'.’.
To require a version of the format that you know to have certain
features, include the optional format-date on which those
features were implemented. If present, it must be in the form
YYYY/MM/DD. If the format version installed on your system is
earlier than format date then you get a warning like this.
You have requested release `2038/01/20' of LaTeX, but only release `2016/02/01' is available.