Rob Seaman said the following on 07/26/2006 04:42 PM:
>> P | meta.code | code is also called an >> enumeration or a labeling >> | of a flag. An example is the >> PixFlags in the SIAP1.0 >> | standard, which is a flag >> whose meaning is well >> | understood within that protocol. >> >> P | meta.code.class | Classification, tide to a >> namespace. >> | In the Hubble namespace, >> galaxies have codes >> | Sa, Sb, SBa, E0 etc > > Users are not going to understand these distinctions. You will see as> many instances of meta.class.code as you do of meta.code.class. You may > see more meta.class instances than anything else.
It is true that there is some ambiguity regarding meta.code and meta.code.class
According to the dictionary,
a code is a coding system used for transmitting messages requiring brevity or secrecy
and
a classification is a group of people or things arranged by class or category
Thus a classification code is a code representing a category within a classification system.
Suppose a user wants to classify a list of observations according to the following categories: 'SCIENCE', 'CALIB', 'ACQUISITON', 'TEST', etc. Those categories are words, not codes. So a new UCD like meta.class is needed. Though one could argue that words are part of the language system and language is a code for human thought ;-)
If you assign shortcuts to the categories ('S' for 'SCIENCE', 'C' for 'CALIB' etc), the correct UCD is meta.class.code since the UCD recommendation says that the order of the atoms induces a hierarchy.
Now the question is: are there codes that are not part of a classification system? If no, I would drop meta.code and all columns previously assigned meta.code.class should be re-assigned meta.class.code.
> If "code" is synonymous with "enum", why not use "enum"? The word
> "code" is horrifically overloaded for other purposes.
Strictly speaking, I don't think a code is an enumeration. An enumeration is a detailed account, in which each thing is specially noticed. However, 'code' and 'enumeration' are sometimes used for the same thing. It is something like a language shortcut. It is not necessarily bad to mention such words in the definition of a UCD since people are used to deal with both of them, it could even make things easier for the user but only AS LONG AS EXAMPLES ARE GIVEN since some other people might start wondering about the true meaning of words in the definition. In that case, they will have to look at the examples and that will solve the ambiguity. That is why we need to provide examples. Learning by example allows to grasp the basics more easily.
> Also, isn't an
> enumeration a modifier of the base UCD? A classification certainly
> could be open-ended - that is, not a code at all. How about:
>
> meta.class;enum
I would say an enumeration is a list of things (codes or not) that belong to a common category within a classification system...
> Which opens up the possibility of constructs like:
>
> meta.id;enum
>
> Which might be used to limit the allowed values to a specific list of
> observing proposals, for instance - say, to those belonging to a
> particular investigator or pertaining to a particular telescope.
... so here I would assign meta.id;meta.class or better meta.id;meta.class.part?
Cheers
Nausicaa
Received on 2006-07-27Z12:29:21