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[fitsbits] The CONTINUE and HIERARCH Conventions Public CommentPeriods



 
 
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  #1  
Old September 6th 07, 05:34 PM posted to sci.astro.fits
William Pence
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Posts: 66
Default [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)
  #2  
Old September 18th 07, 11:39 AM posted to sci.astro.fits
LC's NoSpam Newsreading account[_2_]
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Posts: 23
Default [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.


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  #3  
Old September 19th 07, 08:44 AM posted to sci.astro.fits
Andreas Wicenec
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Posts: 1
Default [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.


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  #4  
Old September 20th 07, 11:42 PM posted to sci.astro.fits
William Pence
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Posts: 66
Default [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)


  #5  
Old September 21st 07, 08:12 AM posted to sci.astro.fits
LC's NoSpam Newsreading account[_2_]
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Posts: 23
Default [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"


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