reledmac : print lemma for \msdata

Question

Here is MWE:

\documentclass{book}
\usepackage{polyglossia}
\setmainlanguage{italian}
\usepackage[series={A},noend,nofamiliar,noledgroup,nopbinverse]{reledmac}
\firstlinenum{1}
\linenumincrement{1}
\firstsublinenum{1}
\sublinenumincrement{1}
\Xsublinesep{}
\sublinenumberstyle{alph}
\begin{document}

\beginnumbering
\pstart%
    When sub-lineation is in effect, the line number counter is frozen and the sub-line \msdata{ABCDEF}counter advances instead. If one of these commands appears in the middle\stopmsdata\ of a line, it doesn’t take effect until the next line; in other words, a line is counted as a line or sub-line depending on what it started out as, even if it changes in the middle
\pend%
% 
\endnumbering

\end{document}

The msdata command prints line number and allows us to print whatever text we want to add to footnote, which generally mentions names of manuscripts containing the relevant part. See this :

However, it appears that there is no way to print a few letters from beginning and end of the sections between \msdata{ABCDEF}counter advances instead. If one of these commands appears in the middle\stopmsdata. This makes it impossible to know what word/phrase/sentence was present in mentioned manuscripts and not present in others.

Is there any way to print one word/few letters from beginning and then dashes.... and then one word/few letters from the end of the mentioned phrase? It should look like this : 2-3 Ms.] ABCDEF > counter....middle or something similar.

Answer 1

First caveat: A completely automatic processing of the text string between \msdata and \msdatastop, such as "reprinting the first and last word and omitting everything in the middle" is not a trivial feat to implement. (It would require regular expressions or some LuaLaTeX magic.)

w.1 w.2 w.3 w.4 w.5 w.6 --> w.1 ... w.6

And it is probably not really desirable either: there is potential for ambiguity, for instance if w1 or w6 is repeated in the same line. It might be better to retain control over the abridgment.

Second caveat: There is currently no easy way in reledmac to store the text string w.1-w.n between \msdata and \msdatastop, the way a command argument (or environment body) can be stored and retrieved (and further processed, as described above). This is because the only argument of \msdata{} isn't the text string w.1-w.n, but the content of the footnote (f.i. the list of manuscripts). And \stopmsdata takes 0 arguments. Currently, the string w.1-w.n isn't stored anywhere.

Compare and contrast \edtext{}{}: the text that you type into #1 is saved and retrieved (typically, printed as lemma) in the footnote. And the command \lemma{} in the #2 of \edtext gives an additional chance to override that lemma, by storing a different string. There is no such mechanism in \msdata{}.

The simplest and safest way would be to use a custom command with two arguments, one being the list of manuscripts and the other the abridged text string w.1 ... w.6. Depending on the desired result, you could use something like this:

\newcommand{\startmscomment}[2]{\msdata{#1\quad #2}}
...
\startmscomment{ABC}{This ... reference.}%
This is the passage I want to reference.%
\stopmsdata

Another approach that I find promising - but is as yet incomplete – would be to build upon the existing command \setmsdatalabel{}. This determines which text string is printed before the lemma separator and before the content of \msdata. The default is "Ms.", but you can feed any text into the argument, and it will be displayed similarly to the lemma of critical footnotes. I believe this is the formally correct way to achieve what you'd like to do; this would be the appeal of using \setmsdatalabel.

\pstart
\setmsdatalabel{Ms.}
\msdata{ABC}
This is the passage I want to reference.%
\stopmsdata
\pend
\pstart
\setmsdatalabel{This ... reference.}   % Changing the prefix mid-document
\msdata{ABC}
This is the passage I want to reference.%
\stopmsdata
\pend

However, since reledmac inserts the notes after the paragraph has been built and split into lines, the value that we store in the macro \setmsdatalabel will be overwritten by later occurrences in the paragraph. This means that all notes in a paragraph get the same value. See the example:

\documentclass{article}
\usepackage{reledmac}
\begin{document}
\beginnumbering
\pstart
\setmsdatalabel{FIRST - This one gets overwritten}  % !!!
\msdata{ABC}First passage I want to reference.\stopmsdata

%
\setmsdatalabel{SECOND - This one overwrites the FIRST}
\msdata{ABC}Second passage I want to reference.\stopmsdata
\pend
%
\pstart
\setmsdatalabel{THIRD - This one gets overwritten}  % !!!
\msdata{ABC}Third passage I want to reference.\stopmsdata

%
\setmsdatalabel{FOURTH - This one overwrites the THIRD}
\msdata{ABC}Fourth passage I want to reference.\stopmsdata
\pend
\endnumbering
\end{document}

I do not have a solution to this, all attempts failed so far, but maybe others can pick up from here.

There is probably a way to patch this, along the lines of this answer on how to store the value of \lemma. Or maybe it is a possible feature request for the package – to make \setmsdatalabel more flexible.