I finished my PhD thesis on a RESTful model for grid computing a few years ago. I did some work on formalizing XML-based descriptors, including units/scaling. You may find that some of the material in Appendix B and C is useful: http://crystal.harvard.edu/~ijstokes/thesis/RESTfulGrid-StokesRees-Thesis.pd... I envisioned two options: i) units were specified in attributes on an element: <memory type="GB"> 2 </memory> ii) units were specified in-line and needed to be parsed: <memory> 2 GB </memory> At the time I felt that "type" provided a more generic modifier on a value than "units", and would allow things like: <start type="USDate">5/21/2009</start> or <start type="EUDate">21/5/2009</start> I provide 5 sets of "type" modifiers: time, frequency, metric, binary, transfer. No rocket science, but perhaps providing an cut-down portion of the schemas will be helpful, so I include them below. Ian <xs:simpleType name="TimeTypeList"> <xs:enumeration value="fs"/> <xs:enumeration value="ps"/> <xs:enumeration value="ns"/> <xs:enumeration value="us"/> <xs:enumeration value="ms"/> <xs:enumeration value="s"/> <xs:enumeration value="sec"/> <xs:enumeration value="second"/> <xs:enumeration value="min"/> <xs:enumeration value="minute"/> <xs:enumeration value="h"/> <xs:enumeration value="hr"/> <xs:enumeration value="hour"/> <xs:enumeration value="d"/> <xs:enumeration value="day"/> <xs:enumeration value="wk"/> <xs:enumeration value="week"/> <xs:enumeration value="mon"/> <xs:enumeration value="month"/> <xs:enumeration value="yr"/> <xs:enumeration value="year"/> <xs:simpleType name="MetricTypeList"> <xs:enumeration value="f"/> <xs:enumeration value="p"/> <xs:enumeration value="n"/> <xs:enumeration value="u"/> <xs:enumeration value="m"/> <xs:enumeration value="K"/> <xs:enumeration value="M"/> <xs:enumeration value="G"/> <xs:enumeration value="T"/> <xs:enumeration value="P"/> <xs:simpleType name="FrequencyTypeList"> <xs:enumeration value="Hz"/> <xs:enumeration value="KHz"/> <xs:enumeration value="MHz"/> <xs:enumeration value="GHz"/> <xs:enumeration value="THz"/> <xs:simpleType name="BinaryTypeList"> <xs:enumeration value="B"/> <xs:enumeration value="KB"/> <xs:enumeration value="MB"/> <xs:enumeration value="GB"/> <xs:enumeration value="TB"/> <xs:enumeration value="PB"/> <xs:simpleType name="TransferTypeList"> <xs:enumeration value="Kb/s"/> <xs:enumeration value="Mb/s"/> <xs:enumeration value="Gb/s"/> <xs:enumeration value="Tb/s"/> <xs:enumeration value="Pb/s"/>