Critical apparatus is a standard feature of scholarly editions in which variant readings and other philological comments are presented to readers as a compressed list immediately following the text, organized by line numbers therein.
Form and content of the apparatus varies from one discipline to another in the humanities. In manuscript studies and literary philology, the app. crit. is generally differentiated from a separate line-by-line commentary, and is devoted narrowly to the documentation of variant readings found in extant witnesses. In epigraphic and papyrological practice, where there is normally only one ancient witness to a text, the apparatus regularly treats divergeant or erroneous readings published by prior editors, alternative restorations and emendations, and comments on form and appearance (e.g., transposition of letters) that cannot be clearly represented in the text itself. Epigraphers and papyrologists often also include a commentary (line-by-line or otherwise) in which more extended discussion of the text and its interpretation and historical significance can be addressed.
EpiDoc recommends choosing between two methods of encoding the sort of information that is traditionally placed in the critical apparatus:
Probably the most commonly used in EpiDoc projects is the external approach (cf. TEI "location-referenced"), in which the apparatus is encoded explicitly in a separate <div type="apparatus"> element. The individual apparatus entries in such an external division are tied back to the text using standard TEI linking attributes (generally loc pointing to line numbers). This method requires relatively simple XSLT to produce acceptable output, but the EpiDoc Example XSLT does not currently cater for this out of the box.
The in-line approach (cf. TEI "parallel segmentation method") makes use of tags placed directly in the text, which can then be interpreted during post-processing for display in a line-by-line form. Currently the only EpiDoc project to have implemented this is the Duke Databank of Documentary Papyri, and any other project wishing to do so would need some significant work on the EpiDoc Example XSLT to get the behaviour it required.
There are a number of features which you may want to appear in your apparatus or in a separate apparatus section, which are not explicitly encoded as apparatus notes with either of the above methods. The EpiDoc example Stylesheets provide some support to render these in several ways.
It is very important to decide on the approach you want to follow and remain consistent to that, to avoid inconsistencies, although both methods are acceptable and independent of the way you may want to display or not your apparatus notes. The fact that you decide to use app in the text, following the in-line approach, does not dictate automatically that you want an apparatus which includes also other features, as the fact that you use the external approach does not dictate that you do not want anything which you have actually encoded in the text to be printed in an apparatus section. These things are determined at the level of the rendering, not with the encoding, and you may chose what to do, as far as you are consistent with yourself.
Although the external-apparatus approach is the recommended way to encode apparatus notes, you may wish not to have to produce one such note in <div[@type='apparatus']> for each choice element you encoded and want in an apparatus. To inform your encoding decision, here you can find a list of the possibilities currently offered by the The EpiDoc example Stylesheets.
Specific guidance for each approach is provided in its own section as follows:
Other pages describing <div>: