Request: Export issue/number field for journal articles by default?

[zoe-translates]

Context

First, please let me know whether I'm correct in saying that currently, the "issue" or "number" field is not exported by default by the fielded formatters (e.g. RIS, where the field IS is lacking). My reading is based on the comparison of this snippet for RIS formatter

export_service/exportsrv/formatter/fieldedFormat.py

Lines 157 to 163 in c4e8db3

	if (export_format == self.EXPORT_FORMAT_REFMAN):
	return (OrderedDict([('doctype', 'TY -'), ('title', 'TI -'), ('author', 'AU -'),
	('aff', 'AD -'), ('pub', 'JO -'), ('volume', 'VL -'),
	('pubdate', 'Y1 -'), ('page', 'SP -'), ('lastpage', 'EP -'),
	('keyword', 'KW -'), ('url', 'UR -'), ('abstract', 'N2 -'),
	('doi', 'DO -'), ('eprintid', 'C1 - eprint:'), ('issn', 'SN -'),
	('endRecord', 'ER -')]))

vs. bibTeX formatter

export_service/exportsrv/formatter/bibTexFormat.py

Line 140 in c4e8db3

('volume', 'volume'), ('issue', 'number'), ('eid', 'eid'),

This results in a missing field in the output where the "issue" or "number" field could have been made available.

Request

I wonder if the support for exporting the issue/number field in the record (see #175 for custom formats) could be extended to the default output of the fielded formatters too.

Further context

Although the issue/number field may not be that useful for the AAS/RAS journals, it is used in many other styles and by authors outside the "core" Astronomy communities.

This problem was found while I was working on zotero/translators#2998. To create a record as the user browsers the ADS, the Zotero translator (data-gathering routine) requests the RIS data from the API (RIS parsing is simple and fast). That was how I noticed that it's missing.

It could have been worked around by the client using the API for custom formats, but that would've been more difficult to maintain on the client side.