example) Maler (1995) and DeRose (1997). Consistency One obvious consideration is that tags and attribute names should use consistent conventions. For example, it would be unusual to create a schema where some element names are camelCase but others use underscores to separate parts of names, or other conventions. Clear and mnemonic names As in other formal languages, good choices of names can help understanding, even though the names per se have no formal significance. Naming the appropriate tag "chapter" rather than "tag37" is a help to the reader. At the same time, this brings in issues of the choice of natural language. A schema to be used for Irish Gaelic documents will probably use the same language for element and attribute names, since that will be the language common to editors and readers. Tag vs attribute choice Some information can "fit" readily in either an element or an attribute. Because attributes cannot contain elements in XML, this question only arises for components that have no further sub-structure that XML needs to be aware of (attributes do support multiple tokens, such as multiple IDREF values, which can be considered a slight exception). Attributes typically represent information associated with the entirety of the element on which they occur, while sub-elements introduce a new scope of their own. Text content Some XML schemas, particularly ones that represent various kinds of documents, ensure that all "text content" (roughly, any part that one would speak if reading the document aloud) occurs as text, and never in attributes. However, there are many edge cases where this does not hold: First, there are XML documents which do not involve "natural language" at all, or only minimally, such as for telemetry, creation of vector graphics or mathematical formulae, and so on. Second, information like stage directions in plays, verse numbers in Classical and Scriptural works, and correction or normalization of spelling in transcribed works, all pose issues of interpretation that schema designers for such genres must consider. Schema reuse A new XML schema can be developed from scratch, or can reuse some fragments of other XML schemas. All schema languages offer some tools (for example, include and modularization control over namespaces) and recommend reuse where practical. Various parts of the extensive and sophisticated Text Encoding Initiative schemas are also re-used in an extraordinary variety of other schemas. Semantic vs syntactic Except for a RDF-related one, no schema language