On 2016-10-30 18:17, Dale R. Worley wrote:
The current RFC Editor preference seems to be that section titles
should capitalize the first and "important" words. Some of the
section titles adhere to this format but the following ones do not:
1. Specification development
4. Security considerations
6. Definition and encoding
7. Defined subtypes
7.1. Generic SFNT font type
7.2. TTF font type
7.3. OTF font type
7.4. Collection font type
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/15dc1b1eb6227cbb88a8e5e719ef55586474c946
1. Specification development
If this section is only relevant to the Internet-Draft, this section
should have a note to the RFC Editor to remove it upon publication.
If it is intended for ongoing development after the Internet-Draft
becomes an RFC, the wording should be revised since, e.g., once an RFC
is published, it is fixed, so "this specification" cannot be
"maintained".
Note to RFC Editor added by
https://github.com/svgeesus/ietf-justfont/commit/106cadf7ba71d6db6bda2c740e31ba7680f6b0be
2. Introduction
The first two paragraphs of this section do not connect easily. It
seems that second paragraph should start like this:
Over time, a number of standard formats for recording font
descriptions have evolved. This document defines a new top-level
Internet media type "font" according to Section 4.2.7 of
[RFC6838]. The subtypes under under this top-level type specify
different representation formats for fonts (e.g. bitmap or outline
formats).
Connecting sentence added
However, "bitmap" and "outline" are just general properties or styles,
not font representation standards, so really those words should be
replaced by the names of specific font representations, say "(e.g.,
bitmap formats like ABC and outline formats like XYZ)".
and parenthetical example removed.
https://github.com/svgeesus/ietf-justfont/commit/23d2944778b3f6b308b8575a092f3bd9e9a9a78c
3. Background and Justification
The names
application/x-font-ttf
application/font-woff
application/font-sfnt
are mentioned in the text as being in current use, but only
application/font-woff is listed as a deprecated alias of a registered
type. The other two should also be listed as deprecated aliases of
the proper new types.
Agreed for application/font-sfnt. I had forgotten that this registration
was in fact completed.
https://github.com/svgeesus/ietf-justfont/commit/76dfc5377a91442b861f47aa9b8273fd010a7728
Not clear what to do for an x- type, which cannot be registered (but is
in use anyway). Is it helpful to formally deprecate it?
The use of application/vns.ms-fontobject should be discussed. It
seems like you'd want it to be a deprecated alias as well, but the
politics of deprecating that name might be complex.
Yes, it should be discussed. This registration is for Embedded OpenType
(EOT).
I created an issue for this
https://github.com/svgeesus/ietf-justfont/issues/22
From the standpoint of regularity, it would seem clear that a font/eot
should be defined.
This internet draft largely formalizes existing practice, where for
example font/ttf is in widespread use. Given that, and given that a)
application/vns.ms-fontobject is already in widespread use, b) the
current Microsoft Edge browser no longer supports EOT; the only use for
this type is legacy Microsoft Internet Explorer browsers, which (being
legacy) will not update to use the new type.
It seems better therefore, to me, to leave application/vns.ms-fontobject
to die quietly in a corner and neither deprecate it nor attempt to
provide a new media type for it.
Discussion welcome.
registered as MIME subtypes under the "application" top-level type
That should be "media subtypes".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/96d94a0b3efe4e0bd10009d70a4b2c396842424e
Secondly, the lack of a top-level type means that there is no
opportunity to have a common set of optional attributes, such as are
specified here.
Media types use the term "parameter" rather than "attribute".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/46243cc5991cac5a2128c9ce34857528b51ec275
The W3C WebFonts WG decided that the situation can be significantly
improved [...]
Is there a reference for this decision? It is a significant part of
the justification for this registration, and so should be documented..
Agreed, informative reference added by
https://github.com/svgeesus/ietf-justfont/commit/bd0bf07ccb4e6bce9c4d86d7af67d37f2818fe5a
the widespread adoption of IANA's recommendations
What "recommendations" are these?
changed to
"Based on the data analysis
presented above, we conclude that it is the presence of simple
and highly intuitive media types
for images that caused their widespread adoption, "
https://github.com/svgeesus/ietf-justfont/commit/fa298417406d991ab168d93bad6a3bc08cc56346
4. Security considerations
Depending on the format used to represent the glyph data the
font may contain TrueType [truetype-wiki], PostScript
[postscript-wiki] or SVG [svg-wiki] outlines and their respective
hint instructions, where applicable.
The construction "may contain ... where applicable" is awkward, as
both parts indicate possible-but-not-mandatory. I suggest removing
"where applicable".
This is trying to say that TrueType outlines may be associated with
imperative hinting instructions; PostScript outlines may be associated
with declarative hinting instructions, and SVG outlines do not have
hinting instructions. Imperative instructions are actual code, which has
the potential to be maliciously constructed.
Reworded as:
"In particular, the hinting instructions for TrueType glyphs
represent executable code which has
the potential to be maliciously constructed (for example,
intended to hang the interpreter)."
https://github.com/svgeesus/ietf-justfont/commit/3b2845a0cee88c7359571ff1fd58bdb0ab3546d1
Many existing (TrueType,
OpenType [opentype-wiki] and OFF, SIL Graphite, WOFF, etc.) font
formats [...]
This reads awkwardly. Better "Many existing font formats (TrueType
[...]) [...]".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/b132414a5668c5f9da6d6a002f74cb92e6fabb17
in a way that would not affect existing font rendering engines and
text layout implementations.
Better "in an upward-compatible way".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/fe90c1e256003cfbd26ab4d5e3346569a4701a48
Indeed, fonts are sufficiently complex, and most
(if not all) interpreters cannot be completely protected from
malicious fonts without undue performance penalties.
The significance of "are sufficiently complex" is unclear. Do you
mean, "fonts are sufficiently complex that most ..."?
Yes. Fixed by
https://github.com/svgeesus/ietf-justfont/commit/50118dc0cbaf4947f5dd12e5c4dd00b93618bf46
5. IANA Considerations
This specification requires IANA to modify the rules for the existing
Internet Media Types registry by adding a new font top-level type in
the standards tree, updating the media types registration form
[Media-Type-Registration], and registering several subtypes.
This is better said:
This specification registers a new top-level type, "font", in the
standards tree; adds it as an alternative value of "Type Name" in the
media types registration form [Media-Type-Registration]; and
registers several subtypes for it.
Also, it helps greatly if all of the IANA registration operations are
within the section titled "IANA Considerations". See RFC 7322 section
4.8.3. So sections 6 and 7 should be demoted to sections 5.1 and 5.2.
Agreed, and fixed by
https://github.com/svgeesus/ietf-justfont/commit/e6a3210bf9e3aaf84b55fa5bf846f9605fd20597
6. Definition and encoding
The "font" as the primary media content type indicates that the
content identified by it requires certain graphic subsystem such as
font rendering engine (and, in some cases, text layout and shaping
engine) to process font data [...]
I think you want "to process it as font data".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/67a2f2c325c1bb479f108761d0d1606d55315ba6
the subtypes defined within a "font" tree will name the specific
font formats.
Since this is, in fact, part of the specification of "font", I think
you want to say it in the present tense, "the subtypes defined within
the "font" tree name the specific font formats".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/c725ff323517f41a20e50b6bc7c76eaaf60c332d
7. Defined subtypes
Would "Subtype Registrations" be more correct? There really aren't
any "undefined subtypes" that are considered to exist.
In this section the initial entries under the top-level 'font' MIME
type are documented.
I think "specified" rather than "documented". Also, change "MIME
type" to "media type".
All agreed; fixed by
https://github.com/svgeesus/ietf-justfont/commit/c339a2cbd152f8c0493681a746ed21be907cade9
Optional parameters:
In general, parameter names seem to be specified using lower case,
though they are case-insensitive, so you may want to lower-case your
parameter name definitions.
Parameter names changed to lowercase in current draft.
https://github.com/svgeesus/ietf-justfont/commit/8bfb3e6c8958b6ce231677c394c3a8aea51230e2
Parameter values which are acronyms left as upper case - is that good
practice?
Should it be made clearer in the current document that these are case
insensitive?
7.1. Generic SFNT font type
This parameter can be used to specify the type of outlines
supported by the font.
I don't think "supported by" is the best here. Perhaps "provided by".
Agreed, and fixed by
https://github.com/svgeesus/ietf-justfont/commit/2afdee1db67350f61bc6c97216a473a7b7d31119
Similarly for other uses of "supported".
I reviewed those, and disagree. The remaining uses of "supported" talk
about code, and whether that code supports or does not support a
particular thing (outline format, feature, etc).
this
optional parameter is a list containing one or more items,
separated by commas, with optional whitespace.
I strongly recommend against allowing whitespace in parameter values.
It seems to be allowed in principle (RFC 6838 section 4.3), but I
expect many processors of media types to misbehave on parameter values
containing whitespace.
Okay (I was not aware that processors were known to misbehave on spaces
in parameter values, and would be interested to know more about that).
I can also see that people might expect to use spaces.
I suspect this comment would benefit from some discussion, so have
opened an issue for it:
https://github.com/svgeesus/ietf-justfont/issues/24
I can see why a comma-separated list is necessary, but that means that
"Values: TTF, CFF, SVG" is not strictly correct. Perhaps something
like the following (and let IANA figure out how to express that in
http://www.iana.org/assignments/media-type-sub-parameters/media-type-sub-parameters.xhtml):
Values: a comma-separated subset of: TTF, CFF, SVG
Similarly for other parameters which can take a comma-separated list
of defined values.
(Deferred until issue discussion has happened)
Parameter definitions seem to need specification of registration
procedures. (See the sub-type-parameter registry mentioned above;
each parameter has a listed registration procedure.)
I'm not quite clear on what is meant here. Registration of new
parameters beyond those specified in this specification?
Issue created:
https://github.com/svgeesus/ietf-justfont/issues/25
Interoperability considerations: As it was noted in the first
paragraph of the "Security considerations" section, the same font
format wrapper can be used to encode fonts with different types of
glyph data represented as either TrueType or PostScript (CFF)
outlines.
This isn't phrased quite right. Perhaps "a single font file can
contain encoding of the same glyphs using several different
representations, e.g., both TrueType and PostScript outlines".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/bc11eae185f596dac69b447e994e7eb0d340b241
Existing font rendering engines may not be able to
process some of the particular outline formats, and downloading a
font resource that contains unsupported glyph data format would
Change "unsupported glyph data" to "only unsupported glyph data" -- as
long as the font contains one format supported by the engine,
downloading the font is useful.
Good catch.
result in inability of application to render and display text.
This seems unlikely; rather the engine would have to use some default
font. So say "... would be futile".
Agreed.
These two fixed by
https://github.com/svgeesus/ietf-justfont/commit/43fe0fd57ddf6ddbb8e4eaf999d82052064bf89e
Therefore, it would be extremely useful to clearly identify the
format of the glyph outline data within a font using an optional
parameter, and allow applications to make decisions about
downloading a particular font resource sooner.
Change "it would be" to "it is", or better, "it is useful to provide a
way to identify the format".
Agreed, fixed by
https://github.com/svgeesus/ietf-justfont/commit/035cb04837c6c1b6367db5e4b916dc84791f54c4
(Which begs the question of whether there is an efficient way for the
browser to determine the media type parameter without downloading the
font -- how does the browser get the media type of the font file without
a GET?)
In principle the Accept header could be used, for classic server-based
content negotiation.
In practice that does not seem to be used, at least by Web browsers;
they send the same formulaic accept regardless of the type of resource
being requested, and most HTTP servers are not set up to support content
negotiation at all..
Similar, another
optional parameter is suggested to identify the type of text
Better as "Similarly, another optional parameter identifies".
Please
note that as new outline formats and text shaping mechanisms may
be defined in the future, the set of allowed values for two
optional parameters defined by this section may be extended.
This should probably be stated under the registration procedures for
the values of these parameters.
Agreed, reworded as suggested and the "Please note" deleted
https://github.com/svgeesus/ietf-justfont/commit/4b05417a335d1cf37f6483b293185fd14258b98e
This possibility is subtly different
from simply adding to a list of allowed values; it warns the
implementation that the sub-values within the comma-separated list may
be unknown and if so, only the known values should be processed.
Indeed, that should probably be said more explicitly:
Registration procedures:
Expert Review (?)
Note that new sub-values may be defined in the future. If an
implementation does not recognize a sub-value in the
comma-separated list, it should ignore the sub-value and continue
processing the other sub-values in the list.
Agreed, Registration procedures moved into section 5 and your suggested
wording added.
https://github.com/svgeesus/ietf-justfont/commit/8ddc9105109c161df21a2ee8cc40bc79189d72cc
Why should, rather than must?
Applications that use this media type: Any and all applications that
"Any and all" sounds rhetorical. Better to say just "All".
Yes
https://github.com/svgeesus/ietf-justfont/commit/0678903b9f920e25eea7dc81f490e009db186fc4
7.2. TTF font type
Similar comments as for section 7.1
Indeed, isn't 7.2 just a subset of 7.1? Why is it separately defined?
It is a subtype, yes. In principle, the sfnt type could be used for TTF,
OTF and Collection
It is separately defined because
a) font/ttf is shorter than font/sfnt; outlines=ttf
b) font/ttf is already in widespread use (despite not yet being
registered; see the data analysis in the informative references) and
this specification is aligning with actual practice.
c) avoiding parameters unless absolutely needed makes server
configuration easier, perhaps
In other words font/sfnt is more of an abstract type, from which the
(widely used in practice) font/ttf and font/otf types are conceptually
derived. Use of font/sfnt is likely to be rare in practice, and might
be confined to
a) uncommon combinations such as font/sfnt; outlines=sil which do not
have a shorter type
b) cases where a new parameter values is registered
c) test cases, experimentation, etc
7.3. OTF font type
Similar comments as for section 7.1
Indeed, isn't 7.3 just a subset of 7.1? Why is it separately defined?
7.4. Collection font type
Similar comments as for section 7.1
Indeed, isn't 7.3 just a subset of 7.1? Why is it separately defined?
Same answers as above regarding subsets.
Same changes to interoperability considerations
https://github.com/svgeesus/ietf-justfont/commit/49d768f1ee382b2279acc1803af149573d5c1317
7.5. WOFF 1.0
Macintosh Universal Type Identifier code: "org.w3c.woff"
Is this part of a media type registration? (If so, is it required for
all "font" subtypes?)
If I recall correctly, this information was added during review on
ietf-types list of the original applications/font-woff media type, in
response to a comment that Macintosh File Type Codes (which we had in
the original proposal, as part of "Additional Information") were being
replaced by Macintosh Universal Type Identifier codes.
The registration is here
https://www.iana.org/assignments/media-types/application/font-woff
I haven't seen any indication that this information is useful or
necessary, and no of know way to check that the information is in fact
correct, or used by macOS.
I would be in favor of dropping it, unless it can be shown that is is
needed and correct.
I raised an issue
https://github.com/svgeesus/ietf-justfont/issues/26
7.6. WOFF 2.0
Fragment Identifiers Optional, for collections encoded as WOFF
Fragment identifiers are always optional, since an HTTP request never
identifies the fragment.
They are optional in an HTTP request. They may not be optional in a url
(if the file is a font collection and the font referred to is not the
first font in the collection.
However, I removed the "Optional".
https://github.com/svgeesus/ietf-justfont/commit/c5df61052d4e2058b8366ea38e22884304d6676d
Fragment Identifiers Optional, for collections encoded as WOFF
2.0. A positive integer. For example, #2 refers to the second
font in the collection. If a fragment is not specified, it is
the same as #1 i.e. the first font in the collection (or the
only font, if it is not a collection). If a fragment is
specified, and the WOFF does not encode a collection, the
fragment is ignored.
This is awkward. Maybe better:
Fragment Identifiers: If the WOFF is not a collection, the only
fragment identifier is "1", which specifies the only font
contained in the object. If the WOFF is a collection, an
integer (1-origin) specifying a font contained in the
collection.
Updated to use your suggested text:
https://github.com/svgeesus/ietf-justfont/commit/c28057591b37c91a2c75e61d732324df7b24091b
Of course, this assumes that the collection has an implicit order, but
I assume that you know that is true.
It is true for a particular revision of a font collection.
The order is not retained between revisions (new fonts may be, and are,
inserted rather than appended when a collection is revised) , which
makes these fragments fragile in certain cases. Use of the PostScript
name, rather than an integer, has been suggested.
See the related issue:
*
**Fragment syntax for collections should be robust against inserting, as
well as appending, new fonts to a collection*
https://github.com/svgeesus/ietf-justfont/issues/18
8. New Registrations
New font formats should be registered using the online form
[Media-Type-Registration]. RFC 6838 [RFC6838] should be consulted on
registration procedures. In particular the font specification must
be freely available and the ABNF must be followed. Also, an @font-
face format should be supplied and, if used, a definition of the
fragment identifier syntax for the new type.
This is really the "registration procedures" for the "font" type. So
I'd move this to section 5.
Done, see above.
I'm not sure what "the ABNF" is that must
be followed, but that seems a redundant statement, as if there is a
prescribed ABNF, then necessarily it must be followed.
Agreed, and that clause removed.
https://github.com/svgeesus/ietf-justfont/commit/16b59b33812ee490eb496439af0bb6df50cbd238
9.2. Informative References
[cff-wiki]
"CFF",<https://en.wikipedia.org/wiki/
PostScript_fonts#Compact_Font_Format>.
This reference isn't referenced in the text.
[postscript-wiki]
"PostScript".
This reference contains no bibliographic information.
It should have, since the source is
<reference anchor="postscript-wiki" target="">
<front>
<title>PostScript</title>
<author><organization/></author>
<date/>
<abstract><t>PostScript (PS) is a computer language for
creating vector
graphics. It is a dynamically typed, concatenative
programming language and
was created at Adobe Systems by John Warnock, Charles
Geschke, Doug Brotz,
Ed Taft and Bill Paxton from 1982 to 1984.</t></abstract>
</front>
</reference>
Ah, I see what happened (both are links to the same wikipedia article,
one to a specific section).
I fixed this by referencing cff-wiki instead of postscript-wiki and
deleting the latter.
https://github.com/svgeesus/ietf-justfont/commit/eaa43e8c9bc26ffecaf8f75f26dbf8d5e5c27ee4
9.3. URIs
If these are intended to be in the final RFC, they should be changed
into proper references. If they aren't intended to be in the final
RFC, this section should have a note to the RFC Editor to delete it.
This section is autogenerated by xml2rfc. However, all three come from
the "Specification development" section, which now contains a note to
the RFC Editor to delete it. Thus, the final RFC should not have this
URIs section.
Many thanks for your thorough review!
To make review easier, I posted an updated draft-04 just now which
contains all the edits made above.
--
Chris Lilley
@svgeesus
Technical Director, W3C Interaction Domain