Ideograms could be either simple or complex. The latter type consisted either of a simple character to which an augmentation was added—e.g., the sign for “mouth” (KA) was secondarily derived from the “head” character (SAG) by superimposing a series of marks over the lower face area—or of a set of linked or nested characters, as in such cases as the signs GU₇ “eat” (which originated as a compound linking the signs SAG and NINDA “food”) and EME “tongue” (formed by inserting the sign with the phonological value me into the KA-sign).

Since a given sign in a text might in principle be read either semantically or phonologically, various clarifying conventions were developed to aid the reader in interpreting the sign sequences. Certain signs (“semantic determinatives”), when added to a word, provided a general semantic key to the intended reading. For example, the character GIŠ (the ideographic value of which was “tree”) could be used as a determinative to identify terms for wooden objects. By adding GIŠ before the sign IG (^gišIG), for example, the scribe was able to indicate that the IG was to be read as the ideogram for “door” rather than as the phonological sequence ik/g/q. The phonological side of the writing system could also be used for clarification. The scribe had the option of incorporating one or more extra accompanying signs (“phonetic determinatives”) to provide a partial indication of the sound of the word represented by the ideogram. A modern English analogue to the cuneiform phonetic determinatives (albeit of much more limited scope) may be seen in spellings such as 1st “first” and 2nd “second.” Using the determinatives, the scribe thus often had several options for rendering words: “door” (Akkadian daltum) could in principle be written by means of an ideogram with a semantic determinative (^gišIG), by an ideogram with a phonetic determinative (^gišIG-tum), or finally by any of several purely phonological renderings (da-al-tum, da-al-tu-um, etc.).

As the use of cuneiform expanded beyond Mesopotamia, the use of ideograms expanded with it. Scribes writing such languages as Elamite, Hurrian, and Hittite adopted Sumerian characters as graphic conventions for rendering words in their own languages. A second stratum of ideograms arose in Anatolia, where Hittite scribes began to use Akkadian words as ideograms. Thus the sign-sequence I-NA became a conventional means of rendering the Hittite preposition anda “in” (Akk. ina), while Hittite keššar “hand” acquired an ideographic spelling ŠU-TI, borrowed from a graphic rendering of Akkadian qàti “hand,” which in turn was composed of the Sumerian ideogram ŠU “hand” and the Akkadian phonetic determinative –ti.

Cuneiform was not the only early Near Eastern script to make use of ideograms. Egyptian hieroglyphs displayed the same dual nature as the Mesopotamian signs, and made similar use of semantic and phonological determinatives. For example, the schematic drawing representing the word “house” (Egyptian pr) was also used to express the consonant-sequence pr. It was thus necessary to distinguish pr “house” from the homographic pr “ascend” by adding to the latter a graphic determinative (based on the drawing of a pair of legs) used as a general marker of motion words.

Although the Old Persian inscriptions were for the most part written phonologically, they also employed a small set of ideograms as an option through which key substantives could be expressed (see table in Kent, Old Persian, p. 12). Like the great majority of the phonological signs of Old Persian, the OPers. ideograms are not formally related to the characters of Mesopotamian cuneiform. The use of ideograms rather than phonological spellings for the words in question became more extensive in later texts. Through the addition of phonological determinatives the scribes were able to express the inflectional endings of words rendered by ideograms. Thus the formula “king of kings” (xšāyaθiya xšāyaθiyānām), which is written out in full in the Bisotun (q.v.) monument, is found abbreviated as XŠ XŠ-y-a-n-a-m in Darius’s Susa A inscription.