control structure
repeat over data-attribute attribute-name of attribute-reference (as alias-name)?
local-scope
again
The repeat over construct can be applied to data-attribute references in the same way
as attribute references.
Inside the repeat over, the data attribute being iterated over can be referred to using either the
data-attribute operator or the attribute operator.
The z format modifier is used to turn off translate rules in order to make the
%v format item behave exactly like the attribute reference.