Reference: attributes

barid attribute

Bar identifier

barid
Type	Element	Description	Use
	bar	Unique bar number identifier	To assign unique sequential numbers to bars

The bar number is indicated with the barid (read bar-id) attribute. Each bar should get its unique identifier name. As there are so many repeated structural elements in music that need unique identifiers, additional id attributes are introduced, of which barid is one.

User agents should number bars sequentially by default, so it should not be necessary for authors to state the barid attribute explicitly, except for a specific purpose.

Example
Markup	What happens...
Long form
<bar barid="1"> <bar barid="2"> ... <bar barid="n">
Short form
<bar 1> <bar 2> ... <bar n>