1. Querying with Units Getting what you asked for IVOA interoperability meeting M Hill (ROE), May 2004

2. Proposal Add markup to language Add markup to language Add analyser to calculate and compare units Add analyser to calculate and compare units –Enough to validate Option: add converters Option: add converters

3. Markup ADQL/x ADQL/x –New Tag ADQL/s ADQL/s –WHERE t.SIZE > 12 [m] Available at all nodes (eg to come) Available at all nodes (eg to come) CDS form? CDS form?

4. Analysis Filling in unspecified Filling in unspecified Catch incompatibilities Catch incompatibilities (example on board) (example on board)

5. Converters Optional Optional Start with simple ones Start with simple ones Build library Build library

6. Tasks Add tags to ADQL/x and ADQL/s Add tags to ADQL/x and ADQL/s Tree walkers Tree walkers Unit interpreters (ie m s-1 * s = m) Unit interpreters (ie m s-1 * s = m) –Just simple algebra? –Just fail if cant do Simple Converters Simple Converters

7. Summary Start simple and grow Start simple and grow At minimum – user informed At minimum – user informed At maximum – user doesnt need to care At maximum – user doesnt need to care Fully traceable (user can see whats been done) Fully traceable (user can see whats been done)