What is alloglottography? A diaeresis? A digamma?
Whose writing system has kanamajiri writing and kokuji?
How would you start to find any of these in a conventional
writing system text/reference, unless you knew where (in
the world) to start? What about opisthograph, ostracon,
quoc-ngu, and tugra? None are in the index of Daniels &
Bright 1996, which I consider the best book to date on
the world's writing systems. But all are entries,
cross-referenced to other entries, in Coulmas's Encyclopedia.
The reader can also look up Bamum writing, Djuka syllabic
writing, the Hatrene script, Hsi-hsia writing, the Loma
syllabary, Peguan script, Tifinagh, Urartian writing, and
the Wolof alphabet directly, without having first to know
what set of writing systems, geographical or typological,
they belong to. My personal favorite is Sogdian writing
(471–74), an Aramaic-derived script used by Persian
colonists in Chinese Turkestan; the cursive form of this
writing system is attributed to Ahriman the devil, because
it is so hard to distinguish the letters. What a pleasant
surprise, for one satiated with discussions of the weaknesses
and unnecessary complexities of Japanese writing!