Ray Plante

In general, I feel this data model is fairly complete (and fun to read). My comments are mainly about presentation. There several things in the definitions that were unclear or ambiguous that I could figure out by looking at the examples. Given that we don't want a standard defined by its examples, we just need put that clarity into the definitions.

To start with, here are some general comments:

• Anywhere there is a formula, it's important to give a full explanation in one of the following forms:
  • a clause that defines each variable (e.g. "where B is the magnetic field"),
  • a reference to published literature where the formula is discussed, or
  • (preferably) both.
  There are places where this is done perfectly (2.1.5.3); other places seem to assume a standard knowledge (2.1.3.19). In this latter case, it may be distracting to spell out the entire formula, particularly when certain ones would be obvious to anyone whose taken a physics class (e.g. ''c'', ''h''), so simply giving a reference should be sufficient. The references (with Rybicki and Lightman, Drake, and Condon/Shortly) seem sufficient to do this. Such references will provide a means for working out ambiguities that we or users may discover later.

• In several places, the document cites the commonly used quantum numbers, e.g. J, M, S, etc., but don't actually explicitly indicate that these are their meanings. I think it would be worthwhile to add a paragraph that defines the subsequent use of these quantum numbers in formulae. It's not necessary to give a full, from-first-principles explanation, but just enough context (and a reference!) to relate the variable names to their common usage as quantum numbers. I'm envisioning something like the following inserted after (or at the end of) the 3rd paragraph on p.5:

  In the definitions of attributes for these concepts, we have adopted the common convention for quantum numbers used by [ref]; that is, where [insert bulleted list from sect 2.1.6.3. with cross-references to appropriate definitions within sect. 6]. We note, however, that an instance of this model can explicitly define the use of these quantum number variables by linking them to their physical definitions (sect. 6).

  In the absence such a paragraph, one can merely provide an explicit explanation of a variable's use (e.g. "where J is the angular momentum quantum number (sect. 6.4.11.)")

• In general when a concept definition invokes another concept defined in the model, an explicit cross-reference would be very helpful.

• Be sure that every concept is explicit about the data type associated with the value that can be given; in particular,
  • indicate explicitly which concepts may be represented by a "PhyscialQuantity" (or equivalent future model). Some numeric values--namely quantum numbers should not be represented as a "PhysicalQuantity"; let's be explicity about this.
  • indicate which are represented by other object classes defined in the document and give the cross reference.

And now for the some specific notes...

-- RayPlante - 16 Sep 2009