reserved prefixes for names

[prjemian]

NeXus will develop and publish a list of reserved prefixes and avoid standardizing any name (specifically, we are thinking of attribute names) that starts with a reserved prefix. To reserve a prefix, post a GitHub issue to the definitions repository.

Should this be generalized to prefix the names of groups, fields, and links, as well?

Originally posted by @prjemian in #757 (comment)

[prjemian]

As noted,

Also suggest that prefixes be easily recognizable, such as capitalized with underscore after, such as PRJ_.

[prjemian]

The manual now has a subsection for reserved field name suffixes, under the section on Naming Conventions. This content is similar. A brief comment should accompany any prefix to describe its intended use.

[prjemian]

Planning to use a table, alphabetized by prefix, such as:

prefix	use	meaning	URL
IDF_	attributes	reserved for use by ISIS Muon Facility	www.isis.stfc.ac.uk
NX	NXDL class	For the class names used with NeXus groups	www.nexusformat.org
NX_	attributes	reserved for use by NeXus	www.nexusformat.org
PDBX_	attributes	reserved for the US protein data bank	www.rcsb.org
SAS_	attributes	reserved for use by canSAS	www.cansas.org/
SILX_	attributes	reserved for use by silx	www.silx.org

Note that unless stated explicitly in the meaning, the reservation applies to any upper or lower case form of the prefix.

[prjemian]

As stated in #757 (comment), reference this subsection in the FAQ.

[prjemian]

Also, search through the manual sections for mentions of reserved prefixes (such as NX reserved for NXDL class names) and create references to this new subsection where appropriate.

[prjemian]

While perusing ancient NeXus history, interesting to note the idea of naming prefixes was discussed previously.

[prjemian]

Note that in NXentry, the attribute IDF_Version is ISIS Muon IDF_Version. Add IDF_ to the list.

[prjemian]

• Check EPICS area detector, that it uses the AD prefix (@MarkRivers)
• Check PDBX_ (protein data bank) URL: https://www.rcsb.org/

[prjemian]

Restrict AD to upper case (since address exists).

[prjemian]

Additional metadata in EPICS area detector matches the prefix NDAttr, for example:

        @NDAttrName = Sample_XTranslation
        @NDAttrDescription = Sample XTranslation [mm]
        @NDAttrSourceType = NDAttrSourceEPICSPV
        @NDAttrSource = 9idcSample:XTranslation
        @NDAttrName = UserName
        @NDAttrDescription = user name listed as GUP PI
        @NDAttrSourceType = NDAttrSourceEPICSPV
        @NDAttrSource = 9idcLAX:UserName
        @NDAttrName = GUPNumber
        @NDAttrDescription = GUP proposal number
        @NDAttrSourceType = NDAttrSourceEPICSPV
        @NDAttrSource = 9idcLAX:GUPNumber

[prjemian]

At NIAC2020:

Prefixes should follow a naming scheme of uppercase letters followed by an underscore, but exceptions will be made for cases already in wide use.

[stuartcampbell]

Just linking nexusformat/NIAC#80 as that discusses and adds a BLUESKY_ prefix