Media Queries – disposition of comments

Also, see disposition of comments from Philipp Hoschka in the disposition of comments to the Last Call.

These are minor editorial comments for your Media Queries Candidate Recommendation...

   images (or image)
   Value: none | bitmap | vector | all
   Applies to: visual media types
   Accepts min/max prefixes: no

@media print{
  @page{
    margin:2cm;
  }
}

I couldn't find it anywhere and I guess it should have been defined in CSS 3 media queries which points to CSS 2.1 (or 2.0, actually) which I believe forbids it. However, the CSS 3 paged media module gives some examples of it which make it same like it is allowed. (And it would make sense.)

@media {}
@media all {}
@media "foo" {}
@media all "foo" {}

What should happen when the name is the empty string? I guess it should work the same way as <link rel=stylesheet title=""> in HTML. In Mozilla and Opera, the empty string is equivalent to no name at all (or the other way around, no name is equivalent to the empty string). Thus, I think the following should be equivalent:

@media all {}
@media all "" {}

  @media all and (orientation: portrait) { ... }
  @media (orientation: portrait) { ... }

@media all and (min-width: 1px), all and (min-width: more than 1px) {
  p { color: green }
}

@media all and (min-width: 1px), all and (unknown-feature: 3px) {
  p { color: green }
}

@media all and (min-width: 1px), all and (min-width: 1unknownunit) {
  p { color: green }
}

@media all and (min-width: 1px), all and ((< min-width 200px)) {
  p { color: green }
}

@media all and (min-width: 1px), all and (width at least 200px) {
  p { color: green }
}

Section 5 does say this:

Since "max-weight" is an unknown media feature, the Media Query is false and the associated style sheet will not be applied.

But it doesn't say how unknown media features are parsed. Is anything unknown within matched parentheses accepted, but considered always false?

This is now clarified in the new error handling section.

@media screen and (color), projection and (color)
 { @import url(http://www.example.com/color) }

Question: To support media's with device-aspect-ratio 16:9 or 2.35 (or more) can the query like this is

@media screen and 
  (device-aspect-ratio: 16/9, 2.35)

@media screen and (device-aspect-ratio: 16/9),
       screen and (device-aspect-ratio: 4/3)

   @media screen and (table) {
      div {display: table}
   }

In the "related work" section, please explain why you could not reuse this syntax (I think I know the answer to this, but it would be good to have it on record)

• embedding a CC/PP description in the document
• referring to an external CC/PP description via a URI

Referring to an external description via a URI was proposed and discussed in the WG. However, an external URL would be expensive to resolve and cache. The proposed syntax builds on, and is compatible with, existing W3C Recommendations. Furthermore, the syntax is very compact and readable.

CC/PP uses URIs for media features, CSS media queries uses a central registry. Using URIs has the additional benefit of providing simpler extensibility and evolvability than a central registry.

Could you address on why you chose to use one central registry, rather than a URI-based solution such as CC/PP?

The term "bitmapped" has been changed to "bitmap".

@media screen { * {font-family: sans-serif}

Relative units in media queries are based on the initial value of that property.

This initial value for some properties could, in turn, be based on user settings. For example, the initial value of 'font-size' is the keyword 'medium' which may be what the user specifies.

The "width" media feature describes the width of the rendering surface of the output device. For continous media, this is the width of the viewport (as described by CSS2). For paged media, this is the width of the page box (as described by CSS2).

• Why can I enquire of the device, but not of the viewport?
• Why can't I just ask if it is landscape or portrait?
• Why aren't there prefixes for this property? max-device-ratio: 1/1 would give me portrait or square; min-device-ratio: 1/1 would give me landscape or square for instance.

The suggestion to allow prefixes on this media feature is good and this has been added to the latest draft.

A { border-width: 1px }
@media all and (scan: interlace) { 
  A { border-width: 2px }
}

For accessibility, this determination should acquire the base font size from the processor, that is to say incorporate the settings of the user inherited by the document from the operating system and browser. How will that happen under the above definition?

I would think that the logical path for this value would be from the user settings into the browser's effective or default stylesheet and from there into the context of the root element of the document, which would inherit it from there. This implies that if a stylesheet asserts an initial font size that this intervenes in the process and overrides the value from the browser. Is this true?

The primary reason for media types being mutually exclusive is to allow authors to write separate style sheets for different media types. For example, a rule tied to the "screen" media type should not influence the presentation on a "handheld" device — even if the handheld device has a screen.

The table below shows the syntax for common logical expressions in RFC 2506 and Media Queries.

Existence-proof Scenario (example of why we care): Blind user with screen reader and speech only -- add 'speak before' etc. generated content is appropriate. BUT Reading-difficulty user with speech augmented reading -- don't introduce anything not on screen. Correct style selection depends on the media combination, not just the medium.

We do understand your example and invite you to put forward a proposal for a new media type name describes the second case. This is a simpler solution than introducing formal logic to describe combinations of existing media types.