  Two superalgebras associated with $p$-branes are the constraint algebra and
the Noether charge algebra. Both contain anomalous terms which modify the
standard supertranslation algebra. These anomalous terms have a natural
description in terms of double complex cohomology of generalized forms. By
retaining fermionic charges and allowing for gauge freedom in the double
complex, it is shown that the algebra of conserved charges forms a spectrum
with free parameters. The spectrum associated with the Green-Schwarz
superstring is shown to contain and generalize the known superalgebras
associated with the superstring.
