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[fitsbits] The CONTINUE and HIERARCH Conventions Public CommentPeriods
First, a reminder that the Public Comment Period on the CONTINUE keyword
convention will be closing soon. Second, the Public Comment Period on the the ESO HIERARCH keyword convention is now open. Detailed information about both of these conventions is available for public review and comment from the FITS registry web page at http://fits.gsfc.nasa.gov/fits_registry.html Comments about these conventions may be posted here on the FITSBITS mail exploder or the sci.astro.fits newsgroup. Minor typographical issues may be sent directly to the authors of the convention. Bill Pence (on behalf of the IAU FITS Working Group) ----------------------------------------------------------- Brief description of the HIERARCH keyword convention: Under the HIERARCH keyword convention, as originally defined by ESO, bytes 10 through 80 of the HIERARCH keyword record contain a series of ASCII strings, or tokens, that serve to hierarchically classify the keyword, followed by an equals sign ('=') which is in turn followed by the keyword value field. An optional comment field may follow the value field. The value and comment fields conform to the rules for free-format keywords, as defined in the FITS Standard document. The following is an example of this convention: HIERARCH ESO INS OPTI-3 ID = 'ESO#427' / Optical element identifier The hierarchical keywords can be mapped into variable names by concatenating the hierarchical tokens together, separating them with the full stop character. For example, the hierarchical keyword shown above corresponds to the variable name ESO.INS.OPTI-3.ID. This ESO convention can be generalized to support keyword names longer than 8 characters, or which contain ASCII characters that would otherwise be prohibited. Some examples are shown below: HIERARCH LongKeyword = 47.5 / keyword has 8 characters and mixed case HIERARCH XTE$TEMP = 98.6 / This keyword name contains the '$' character -- __________________________________________________ __________________ Dr. William Pence NASA/GSFC Code 662 HEASARC +1-301-286-4599 (voice) Greenbelt MD 20771 +1-301-286-1684 (fax) |
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[fitsbits] The CONTINUE and HIERARCH Conventions Public CommentPeriods
I have inspected the PDF description of the HIERARCH Convention in the
registry and I have the following questions/comments. 0) Who is the author (or authority) which issued such document ? 1) I was of course aware of the usage of the HIERARCH convention at ESO and I think section 1 of the document provides an adequate documentation of the generalized hierarchical convention while leaving ESO specific details to the (quoted) DICB 2) The key characteristics of the general convention described in section 1 is that the first token defines a namespace. So any further details for namespace ESO are correctly referred to ESO documentation. Did anybody else use their own namespaces ? And who is the authority to prevent conflicts in the creation of namespaces ? 3) Although defined in a self-consisent manner, the content of section 2 is DEFINING AN ALTOGETHER DIFFERENT CONVENTION ! In section 2 there is no namespace, or any token is a namespace of its own. This seems to me a rather bad and confusing idea. It has nothing to with an "hierarchical" organization Unless such usage is already in widespread diffusion, I think we should try to stop it, and replace it with some cleaner alternative - define a specific namespace for long keywords e.g. one of HIERARCH LONGKWDS anysinglelongtoken = value / comment HIERARCH LONG anysinglelongtoken = value / comment (although this is a misuse of the name and a little space waste) - define an altogether new convention (with the same syntax of HIERARCH but eventually specifying there is a single token, and with the keyword name itself replaced by something else) LONGKWDS anysinglelongtoken = value / comment i.e. the 8-char kwd name is LONGKWDS, char 9 is blank so it is formally a commentary type keyword, and for the rest as for HIERARCH but ntoken=1 My idea is that we should register section 1 only as description of HIERARCH and perhaps register a separate LONGKWDS convention somehow replacing section 2. -- ---------------------------------------------------------------------- is a newsreading account used by more persons to avoid unwanted spam. Any mail returning to this address will be rejected. Users can disclose their e-mail address in the article if they wish so. |
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[fitsbits] The CONTINUE and HIERARCH Conventions Public CommentPeriods
I fully agree with the points given here by whoever that was...
Andreas Wicenec On 18.09.2007, at 12:39, LC's NoSpam Newsreading account wrote: I have inspected the PDF description of the HIERARCH Convention in the registry and I have the following questions/comments. 0) Who is the author (or authority) which issued such document ? 1) I was of course aware of the usage of the HIERARCH convention at ESO and I think section 1 of the document provides an adequate documentation of the generalized hierarchical convention while leaving ESO specific details to the (quoted) DICB 2) The key characteristics of the general convention described in section 1 is that the first token defines a namespace. So any further details for namespace ESO are correctly referred to ESO documentation. Did anybody else use their own namespaces ? And who is the authority to prevent conflicts in the creation of namespaces ? 3) Although defined in a self-consisent manner, the content of section 2 is DEFINING AN ALTOGETHER DIFFERENT CONVENTION ! In section 2 there is no namespace, or any token is a namespace of its own. This seems to me a rather bad and confusing idea. It has nothing to with an "hierarchical" organization Unless such usage is already in widespread diffusion, I think we should try to stop it, and replace it with some cleaner alternative - define a specific namespace for long keywords e.g. one of HIERARCH LONGKWDS anysinglelongtoken = value / comment HIERARCH LONG anysinglelongtoken = value / comment (although this is a misuse of the name and a little space waste) - define an altogether new convention (with the same syntax of HIERARCH but eventually specifying there is a single token, and with the keyword name itself replaced by something else) LONGKWDS anysinglelongtoken = value / comment i.e. the 8-char kwd name is LONGKWDS, char 9 is blank so it is formally a commentary type keyword, and for the rest as for HIERARCH but ntoken=1 My idea is that we should register section 1 only as description of HIERARCH and perhaps register a separate LONGKWDS convention somehow replacing section 2. -- ---------------------------------------------------------------------- is a newsreading account used by more persons to avoid unwanted spam. Any mail returning to this address will be rejected. Users can disclose their e-mail address in the article if they wish so. _______________________________________________ fitsbits mailing list http://listmgr.cv.nrao.edu/mailman/listinfo/fitsbits |
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[fitsbits] The CONTINUE and HIERARCH Conventions Public CommentPeriods
LC's NoSpam Newsreading account wrote:
I have inspected the PDF description of the HIERARCH Convention in the registry and I have the following questions/comments. .... 3) Although defined in a self-consisent manner, the content of section 2 is DEFINING AN ALTOGETHER DIFFERENT CONVENTION ! Both of these (the ESO hierarchical usage, and the long keyword name usage) are special cases of the more general convention that has been implemented in CFITSIO since 1999. The general convention looks like this: HIERARCH Effective Keyword Name = value / Comment String where Effective Keyword Name represents any string of ASCII text characters (except the equal sign character which is not allowed because it serves as the delimiter between the Effective Keyword Name and the value. Examples of this general convention a HIERARCH Last Name = 'Pence' HIERARCH $PATH = '/usr/local/bin /usr/bin/' HIERARCH Minimum Disk Space Requirement = 3000000 / bytes In this general case there are no restrictions on what characters are allowed in the Effective Keyword Name, except for the equal sign character, and that it must fit within the 80-character keyword record. In the CFITSIO API, programs can read and write keywords such as "Last Name" or "$PATH" in exactly the same way as they would read or write a standard keyword like "OBJECT" or "DATE". The application program itself does not need to know how the HIERARCH convention works. In the ESO special case, the Effective Keyword Name consists of a series of tokens that each conform to the requirements of a FITS keyword name. The first token defines the name space, and the remaining tokens form a hierarchical classification of the keyword. In the long keyword name special case, embedded spaces are not allowed to avoid confusion with the ESO usage, and to avoid problems that can arise in handling the embedded spaces in certain circumstances (e.g., it can make it more difficult to parse the keyword record). Bill -- __________________________________________________ __________________ Dr. William Pence NASA/GSFC Code 662 HEASARC +1-301-286-4599 (voice) Greenbelt MD 20771 +1-301-286-1684 (fax) |
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[fitsbits] The CONTINUE and HIERARCH Conventions Public CommentPeriods
On Thu, 20 Sep 2007, William Pence wrote:
Both of these (the ESO hierarchical usage, and the long keyword name usage) are special cases of the more general convention that has been implemented in CFITSIO since 1999. The general convention looks like this: HIERARCH Effective Keyword Name = value / Comment String where Effective Keyword Name represents any string of ASCII text characters (except the equal sign character which is not allowed because it serves as the delimiter between the Effective Keyword Name and the value. OK, if you have enough evidence that the full convention as supported by CFITSIO is in use (beyond the ESO and long keyword cases) then the definition above should appear FIRST in the document for the registry ! My only comment then could be that HIERARCH is a misnomer, but that should be accepted on historical grounds. In the ESO special case, the Effective Keyword Name consists of a series of tokens that each conform to the requirements of a FITS keyword name. In the long keyword name special case, embedded spaces are not allowed to avoid confusion with the ESO usage, These should than be presented in the document as two clear subconventions of the general case. My suggestion are : - to call the convention "Generalized keyword (HIERARCH) convention" - to copy your general definition in a prominent place at beginning of the document - to call the first subconvention "hierarchical (tokenized) subconvention" ... the ESO case will be a sub-sub-case where the first token is 'ESO' ! - to call the second subconvention "long keyword subconvention" -- ---------------------------------------------------------------------- is a newsreading account used by more persons to avoid unwanted spam. Any mail returning to this address will be rejected. Users can disclose their e-mail address in the article if they wish so. |
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