@ -- Assignments of tags to baselines.  Note that we allow tags to
@ -- have values assigned to them.  So we are not really dealing with
@ -- tags here.  These are really properties.  But we are going to
@ -- keep calling them tags because in many cases the value is ignored.
@ --
@ CREATE TABLE tagxref(
@   tagid INTEGER REFERENCES tag,   -- The tag that added or removed
@   tagtype INTEGER,                -- 0:-,cancel  1:+,single  2:*,propagate
@   srcid INTEGER REFERENCES blob,  -- Artifact of tag. 0 for propagated tags
@   origid INTEGER REFERENCES blob, -- check-in holding propagated tag
@   value TEXT,                     -- Value of the tag.  Might be NULL.
@   mtime TIMESTAMP,                -- Time of addition or removal
@   rid INTEGER REFERENCE blob,     -- Artifact tag is applied to
@   UNIQUE(rid, tagid)
@ );