Hieroglyphic Hittite and Cuneiform Hittite in Boǧazköy
Around the time of World War I thousands of cuneiform texts were uncovered in excavations in Boǧazköy in Central Anatolia. The texts featured many languages. Among the Indo-European languages were cuneiform Hittite, hieroglyphic Hittite, Luwian, and others. Among the non-Indo-European languages were Hurrian, Akkadian, Sumerian, and others. The "chief among the Boǧazköy languages," according to G. Bonfante and I. J. Gelb, was cuneiform Hittite.
Bonfante and Gelb co-authored "The Position of 'Hieroglyphic Hittite' Among the Indo-European Languages" (1944), in which they explain that cuneiform Hittite was the official language of the Hittite state. This is evident in the fact that this language was used for the "historical annals, proclamations, laws, and treaties with foreign countries." The language was also used in religious literature (rituals, oracles, prayers) and mythology (a fragment of Gilgamesh was written in cuneiform Hittite).
Hieroglyphic Hittite was also used, although in different types of media. Hieroglyphic Hittite was used on royal seals on clay bullae and on clay tablets, according to Bonfante and Gelb. They observed that no royal seals were written in cuneiform Hittite and no non-royal seals that were discovered at Boǧazköy were in cuneiform Hittite.
The most fascinating question to consider is the relationship between hieroglyphic Hittite and cuneiform Hittite. In the New Hittite period, "the most interesting feature of the bilingual seals is that the royal names in the Akkadian are different from the royal names in hieroglyphic Hittite." Different names were used for royalty in cuneiform languages than in hieroglyphic Hittite. So, Bonfante and Gelb ask, "why did these kings use names in hieroglyphic Hittite which were different from their names in cuneiform Hittite?" An explanation is given:
"Cuneiform Hittite was the language of the Boǧazköy area which was later conquered by kings of hieroglyphic Hittite origin. In spite of the conquest, the native cuneiform Hittite was able to assert itself as the state language of the New Hittite Empire; but hieroglyphic Hittite was used by the kings and perhaps by the nobility who came with them. The kings retained their true hieroglyphic Hittite names and used them on their seals as well as on the hieroglyphic Hittite inscriptions scattered throughout Anatolia. At the same time they accepted second names traditional in the native Hittite state, which they used in cuneiform Hittite."This means the people kept their administrative (legal, historical, etc.) documentation in their native language and the conquering Hittite rulers kept their royal functions (names and seals). This means the two languages coexisted within one area, each with a separate use.
Bonfante, G. and I. J. Gelb, "The Position of 'Hieroglyphic Hittite' among the Indo-European Languages," Journal of the American Oriental Society, Vol. 64, No. 4 (Oct–Dec. 1944), pp. 169–190.