p-brane spectra and charge quantisation

We discuss the character of the p-form charges carried by p-brane solutions to supergravity theories. The antisymmetric tensorial nature of these charges gives rise to a new feature of the Dirac quantisation condition, that there are "Dirac-insensitive" configurations. Although they constitute only a measure-zero, set, the existence of these insensitive configurations is important because they are needed to understand the pattern of Dirac conditions in lower dimensions obtained by dimensional reduction.