A change in the shape of one of the 50 basic strokes is implicitly applied within each character that embeds that stroke. Likewise, a change to a component is implicitly applied within each and all characters whose assemblage uses that component. T. Bishop and R. Cook explain this as follows: nearly 100,000 Chinese characters have been described via CDL. HanGlyph A character description language intended for supplying missing rare characters in documents (addressing the Chinese equivalent of the gaiji problem). Documents can contain markup for missing characters, which will automatically trigger the generation of small fonts to provide the characters. The language itself is a simple postfix notation describing strokes and ways to combine them. The prototype software uses Metapost to render the characters and embed them in LaTeX documents. The language was presented by Wai Wong in 1997, and papers about its implementation in Metapost and LaTeX appeared at TeX user group conferences in 2003. Ideographic Description Sequences Chapter 12 of the Unicode specification defines a syntax for "Ideographic Description Sequences" (IDSes) intended for use in describing characters not included in the standard in terms of combinations of components that do have code points. Twelve special characters in the range U+2FF0 to U+2FFB act as prefix operators to combine other characters or sequences to form larger characters. These sequences are useful in describing to the reader a character that is not directly printable, either because it is absent in a given font, or is absent from the Unicode standard altogether. For example, the Sawndip character "" (encoded in CJK Unified Ideographs Extension F as U+2DA21 𭨡) can be described as "⿰書史". Another use is for dictionary lookup purposes, as a sort of rough input method for queries. These sequences can be rendered either by keeping the individual characters separately or by parsing the Ideographic Description Sequence and drawing the ideograph so described. They do not, by themselves, provide unambiguous rendering for all characters. For instance, the sequence ⿱十一 represents both 土 ("soil", the middle bar being narrower) and 士 ("bachelor", the middle bar being wider). Unicode's specification for these sequences is based on the characters and syntax of the earlier GBK standard. The IDSgrep free software package by Matthew Skala extends Unicode's IDS syntax to include additional features for dictionary lookup; it is capable of converting KanjiVG's database to its own extended IDS format, or of searching EIDS files