Release 3.6.0, the “Potrzebie” release of the TEI Guidelines is a celebration of and its invention of an imaginary Potrzebie system of measurement in its early issues. The name is especially fitting due to a combination of factors: ceases publication of new issues in August 2019, and the Potrzebie system is represented in an example accompanying a major feature of this TEI release: a way of defining nonstandard systems and units of measurement.

The release introduces this and other new features, and it resolves a number of issues raised by the TEI community. As always, the majority of these changes and corrections are a consequence of feature requests or bugs reported by the TEI community using the GitHub tracking system. A full list of the issues resolved in the course of this release cycle may be found under the 3.6.0 milestone.

The following changes are particularly worth highlighting in this release: New elements, attribute classes, and attributes have been introduced to provide information about units of measurement that are not listed in the International System of Units, and to document how to convert between systems of measurement (#1707): The unitDecl element provides information about units of measurement that are not members of the International System of Units. The unitDef element contains descriptive information related to a specific unit of measurement. The conversion element defines how to calculate one unit of measure in terms of another. The fromUnit attribute indicates a source unit of measure that is to be converted into another unit indicated in toUnit. The toUnit attribute provides the target unit of measurement for a conversion from a source unit referenced in fromUnit. A new attribute formula allows for specification of a mathematical formula in XPath. Currently the only member of the new class is the new conversion element. The formula is introduced in a new attribute class, att.formula, since it may be applicable to a wider range of applications than conversion between units of measure. The unitRef attribute, a pointer alternative to the unit attribute, has been added to the att.measurement attribute class. (#1905). The unitRef attribute is designed for pointing to an xml:id on the new unitDef element. Guidelines prose has been written for in chapter 2.3.9, and a range of supporting examples of the new elements and attributes associated with it are provided. A new class model.fsdDeclPart has been introduced. fLib, fsDecl, fsdLink, and fvLib are now members of this class (#1726). The note element is now available within the witness element (#1728). The suggested values of the unit attribute have been regularized (#1740). The definition of the msFrag element has been clarified (#1747 and #1832). More explanation is provided in the Guidelines on prosopographies referring to authoritative external resources on named entities using idno, in 13.3.1 in response to #1414. The idno element is now available for event; the ptr element is available for event, person, place, and org (#1756). The examples of the selector attribute of the rendition element have been revised, according to CSS (#1766). The desc element has been added to the content model of the members of model.listLike (#1771). The trailer element is now a member of att.placement and att.written (#1778). The use of the lem element within a single apparatus entry has been clarified, whether it appears outside a rdgGrp element or within it (#1785). The examples of the biblStruct element have been revised by moving the members of the class model.ptrLike to the right location; an additional example has been added (#1788). The entry element is now a member of model.entryPart.top (#1791). The date and time elements are now members of att.canonical (#1821). The listRef element is now a member of att.typed (#1803). The constraint for processing child elements of certain kinds of lists has been loosened in the schema (#1829). The descriptions of the elements depth, height, and width have been revised (#1850). Files that are generated during the local build of the Guidelines have been added to .gitignore (#1898, thanks to Duncan Paterson). The mismatch for the documentation of values for the expand attribute of the classRef element has been corrected. (#1903). Corrections of typographic errors, improvements on explanations, and corrections of examples have been conducted in various sections of the Guidelines (including #1816).

Furthermore, a number of translations have been added or updated. For the Japanese translations, we especially thank Kiyonori Nagasaki and his formidable team, along with Hanna McGaughey .

Documentation of Council practices in TCW 20 is improved for referencing figures more precisely and for more consistently writing Schematron constraints using standard Schematron values for the role attribute.

In addition, many improvements have been made to the XSLT stylesheets (which provide processing of TEI ODD files for Roma and OxGarage as well as other TEI conversions). The Stylesheets are maintained separately from the Guidelines and are at https://github.com/TEIC/Stylesheets. A full list of the issues resolved in the course of this release cycle may be found under the 7.48.0 milestone.

Highlights of this release include: Handling of multiple schemaSpec elements when merging multiple Spec* declarations (#249). Clarification of the creation and use of the TEIVERSION processing instruction (#355). Elimination of extra space before semicolon in list of suggested values in RELAX NG (#357). Support for preserving manual page breaks (#358). Handling element names linking to their individual spec pages in the PDF version of the Guidelines’ PDF (#360). Added namespace to egXML examples in egXML output (#361). The ODD processing has been enhanced to allow for multiple declarations of sch:ns within schemaSpec (#366). The broken links in the ePub version have been fixed (#375). The support of examples in the schema has been improved (#383).