A variant on Raphink's answer: define a macro like
(i.e. not using
\newcommand). This makes a "delimited macro" using a plain TeX construction, where the 2011abc part is not actually in the name of the macro but is required to be present when the macro is expanded. The actual name of the macro is
\ABC, so this is prone to unexpected errors if you also define
For some reason, this gives bizarre results using
\newcommand, probably because of how it internally processes the macro name to check that it was not previously defined.