Copyright © 2014-2016 Bert Frees
This module builds on braille CSS [BRAILLECSS] and defines a set of properties, values and pseudo-elements specific to OBFL-based [OBFL] agents.
This document is merely a public working draft of a potential specification. It has no official standing of any kind and does not represent the support or consensus of any standards organisation.
The features defined in this document are intended to be temporary solutions. The goal is to define official braille CSS features that can be made to work the same across all agents. In order to make the distinction clear all properties, values and pseudo-elements defined here have an ‘-obfl-’ prefix.| Name: | -obfl-vertical-positioning |
|---|---|
| Value: | <length> | auto |
| Initial: | auto |
| Applies to: | block | list-item |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
| Name: | -obfl-vertical-align |
|---|---|
| Value: | before | center | after |
| Initial: | after |
| Applies to: | block | list-item |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
These properties map directly to the block attributes vertical-position and vertical-align in OBFL. Lengths must be non-negative.
| Name: | -obfl-underline |
|---|---|
| Value: | <braille-character> | none |
| Initial: | none |
| Applies to: | block | list-item |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
This property maps to a combination of OBFL block attributes underline-style, underline-align and underline-width.
This module extends the content property with the -obfl-evaluate() function, which evaluates an “OBFL Evaluation Language” [OBFLEVAL] expression. -obfl-evaluate() is added to the list of possible values in the definition of <content-list>.
-obfl-evaluate() = -obfl-evaluate( <string> )
The string argument must be a valid OBFL Evaluation Language expression. In addition, the variables used in the expression must be available in the context of the element on which the content property with the -obfl-evaluate() value is specified. Available variables are:
Braille CSS [BRAILLECSS] defines the display property with possible values block, inline, list-item, and none. This module extends the possible values with -obfl-toc.
The -obfl-toc value corresponds in OBFL with a toc-sequence element that is backed by a table-of-contents element. The content of the table-of-contents element in OBFL corresponds with the content of the -obfl-toc element in CSS. The -obfl-toc value only applies to elements that are placed into a volume area through the mechanism of named flows.
| Name: | -obfl-toc-range |
|---|---|
| Value: | document | volume |
| Initial: | document |
| Applies to: | -obfl-toc |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
This property maps directly to the range attribute of the toc-sequence element in OBFL.
The ::-obfl-on-toc-start, ::-obfl-on-volume-start, ::-obfl-on-volume-end and ::-obfl-on-toc-end pseudo-elements correspond directly with the on-toc-start, on-volume-start, on-volume-end and on-toc-end elements in OBFL. These pseudo-elements only apply to elements with a display value of -obfl-toc.
| Name: | -obfl-table-col-spacing |
|---|---|
| Value: | <length> |
| Initial: | 0 |
| Applies to: | table |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
| Name: | -obfl-table-row-spacing |
|---|---|
| Value: | <length> |
| Initial: | 0 |
| Applies to: | table |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
| Name: | -obfl-preferred-empty-space |
|---|---|
| Value: | <length> |
| Initial: | 2 |
| Applies to: | table |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
These properties map directly to the table-col-spacing, table-row-spacing and preferred-empty-space attributes of the table element in OBFL. Lengths must be non-negative.
A volume-break-inside property with a -obfl-keep() value maps to the OBFL block attribute volume-keep-priority.
-obfl-keep() = -obfl-keep( <integer> )
The function argument defines the priority. It must be an <integer> between 1 and 9.
| Name: | -obfl-keep-with-previous-sheets |
|---|---|
| Value: | <integer> |
| Initial: | 0 |
| Applies to: | block | list-item | table |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
| Name: | -obfl-keep-with-next-sheets |
|---|---|
| Value: | <integer> |
| Initial: | 0 |
| Applies to: | block | list-item | table |
| Inherited: | no |
| Media: | embossed |
| Computed value: | specified value |
These properties map directly to the block attributes keep-with-previous-sheets and keep-with-next-sheets in OBFL. Values must be non-negative.
| Name: | -obfl-use-when-collection-not-empty |
|---|---|
| Value: | <custom-ident> | normal |
| Initial: | normal |
| Applies to: | all elements |
| Inherited: | no |
| Media: | embossed |
| Computed value: | the specified value |
If the value identifies a named flow through which content has passed, the element behaves normally, otherwise it generates no boxes (as if the display property were set to none).