In some cases, when you attempt to create a URL mapping and use certain label name (for example, "pw"), you get an exception such as: "EJPEC0910E: AbstractMappingURLCommand: label pw is invalid."
As documented in the section "The administrative model of URL Mapping" of the IBM Websphere Portal v7 wiki, a label must not have the same name as the URL codecs that are used in Portal because that would introduce an ambiguity when parsing the complete URL.
The reserved names are mentioned in the IBM Websphere Portal v7 wiki on this page:
The list contains these reserved names:
base64xml, b0, b0_1, b0_2, b0_3, b1, b2, b3, c0, c0_1, c0_2, c1, c2, c3, c4, c4_1, c4_2, c4_3, c5, c6, c7, cxml, cxmld, cxml_1, cxml_2, d0, d1, d2, d3, d4, d5, delta, dl2, dl3, dl4, kcxml, nm1, nm2, nm3, nm4, pw, resource, sel, vp, wml
If you are having the same issue with some label names not in this list, please report them to IBM Websphere Portal support via a PMR for further investigation.