Despite the pictorial nature of the oracle bone script, it was a fully functional and mature writing system by the time of the Shang dynasty, meaning it was able to record the
Old Chinese language, and not merely fragments of ideas or words. This level of maturity clearly implies an earlier period of development of at least several hundred years. From their presumed origins as pictographs and signs, by the Shang dynasty, most graphs were already conventionalized in such a simplified fashion that the meanings of many of the pictographs are not immediately apparent. Without careful research to compare these to later forms, one would probably not know that these represented 'swine' and 'dog' respectively. As William G. Boltz notes, most of the oracle bone graphs are not depicted realistically enough for those who do not already know the script to recognize what they stand for; although pictographic in origin, they are no longer pictographs in function. Boltz instead calls them
zodiographs, emphasizing their function as representing concepts exclusively through words. Similarly, Qiu labels them
semantographs. By the late Shang, oracle bone graphs had already evolved into mostly non-pictographic forms, including all the
major types of Chinese characters now in use. Loangraphs, phono-semantic compounds, and associative compounds were already common. One structural and functional analysis of the oracle bone characters found that they were 23% pictographs, 2% simple indicatives, 32% associative compounds, 11% phonetic loans, 27% phono-semantic compounds, and 6% undetermined. , and
regular script characters for 'autumn' Although it was a fully functional writing system, the oracle bone script was not fully standardized. By the early
Western Zhou period, these traits had vanished, but in both periods, the script was not highly regular or standardized; variant forms of graphs abound, and the size and orientation of graphs is also irregular. A graph when inverted horizontally generally refers to the same word, and additional components are sometimes present without changing the meaning. These irregularities persisted until the standardization of the
seal script during the
Qin dynasty. There are over 30,000 distinct characters found from all the bone fragments so far, which may represent around 4,000 individual characters in their various forms. The majority of these still remain undeciphered, although scholars believe they can decipher between 1,500 and 2,000 of these characters. One reason for the difficulty in decipherment is that components of certain oracle bone script characters may differ in later script forms. Such differences may be accounted for by character simplification and/or by later generations misunderstanding the original graph, which had evolved beyond recognition. For instance, the standard character 'autumn' now appears with the components 'plant stalk' and 'fire', whereas the oracle bone form depicts an insect-like figure with
antennae – either a
cricket or a
locust – with a variant depicting fire below said figure. In this case, the modern character is a simplification of an archaic variant (or ) which is closer to the oracle bone script form – albeit with the insect figure being confused with the similar-looking character for 'turtle' and the addition of the component. Some characters are only attested in the oracle bone script, dropping out of later usage and usually being replaced by newer characters. An example is a fragment bearing character for 'spring' that has no known modern counterpart. In such cases, available context may be used to determine the possible meaning of the character. In other cases, the character may be assumed to be a
phono-semantic compound, and a rough meaning can be inferred based on the semantic component. For instance, an oracle bone character was recently found which consists of on the left and on the right ([] when converted from oracle bone forms to their modern printed equivalents. This character may reasonably be guessed to a compound with 'altar' as the semantic and (modern reading
sheng) as the phonetic. Though no modern character consists of these two components, it likely refers to a type of Shang dynasty ritual with a name similar to the pronunciation of in Old Chinese. In the same collection of fragments, the character was surmised to be a place name, since the semantic component means 'mound', 'hill', and the divination concerned the king traveling for a
royal hunt. == Zhou-era inscriptions ==