Proposal for New DAISY SVG Layers

An SVG file may contain objects arranged in physical layers or elements grouped in a hierarchy.  These are irrelevant to the present discussion.  DAISY layers are a new non-hierarchal creation designed to permit one to assign flexible group-type properties to SVG text and objects independent of how they have been grouped by authors. 

Proposed Specification

SVG text and objects may have a DAISY layer attribute permitting them to be assigned to one or more DAISY layers.  The DAISY layer attribute consist of a list of one or more comma separated layer ids. 

DAISY Layers can have attributes including at least:

• Layer id tag
• Layer Title
• Layer Description
• Visible (yes or no)
• Printable (yes or no)
• Embossable (yes or no)
• Active (yes or no)

Brief explanatory notes

• Layer Titles and Descriptions are given by the author to be helpful to end users and are localizable.  For example layers with state objects would presumably have English title "States", a layer with cities would be titled "Cities", or there could be several city layers with titles such as "Capital Cities", "Large cities", etc. 
• The "Visible" attribute allows the user to show or not show the layer on screen. 
• The "Printable" attribute determines whether the layer will print when the SVG image is printed on a printer that can print ink/toner images. 
• The "Embossable" attribute determines whether a layer will emboss when printed to an embossing printer. 
• The "Active" attribute determines whether objects in the layer react to events such as being selected by touch.  If active, typically the title of a graphical object will be spoken, or a sound file played, or some link exercised.  These actions will be forbidden if the layer is not active. 
• Objects and text may be in several different layers that could have different visible, printable, embossable, or active attributes.  The "yes" attribute takes precedence.
• All layer attributes have a default value defined within the SVG file.