<milestone> marks a boundary point separating any kind of section of a
text, typically but not necessarily indicating a point at which
some part of a standard reference system changes, where the change
is not represented by a structural element. 3.10.3 Milestone
Elements
passages present in the text, but not to be included
as part of the reference.
Note
If the milestone marks the beginning of a piece of text not
present in the reference edition, the special value absent
may be used as the value of unit. The normal interpretation
is that the reference edition does not contain the text which follows,
until the next milestone tag for the edition in question is
encountered.
In addition to the values suggested, other terms may be appropriate
(e.g. Stephanus for the Stephanus numbers in Plato).
For this element, the global n attribute indicates the new number or other value for the unit which changes
at this milestone. The special value unnumbered should be used in
passages which fall outside the normal numbering scheme, such as
chapter or other
headings, poem numbers or titles, etc.
The order in which milestone elements are given at a given point is not normally
significant.