Many TAN elements contain multiple values or have attributes that allow multiple
values. Do those multiple values represent intersection, union, or distribution? For
example, attribute="A B"
could be interpreted to mean, using the diagram
below, anywhere in y (intersection); anywhere in x, y, or z (union); or somewhere x
or y and somewhere in y and z (distribution).
Multiple values in TAN are defined according to perceived common usage in ordinary English:
Union (= x, y, or z; default). Examples: anything
that takes the the section called “IRI + name Pattern”, <equate>
, <period>
, <where>
.
Intersection (= y only). Examples: @adverb
and other qualifications of
claims. For example, "...probably not..." does not mean "...probably..." and
"...not..."
Distribution (= x or y and y or z).
@affects-element
,
@claimant
, @object
, <object>
, @src
, @subject
, <subject>
, @verb
. For example, "[Source A], [source
B], are Z" means "Source A is Z" and "Source B is Z."
The discussion above does not treat the important question of range. If an assertion is made about A, is it true for one point in x or y, or is it true for any and all points in x and y? At present, TAN does not address this ambiguity, and leaves the interpretation open.