<lem>

<lem> (lemma) contains the lemma, or base text, of a textual variation. [13.1 The Apparatus Entry, Readings, and Witnesses]
Module textcrit — Critical Apparatus
Attributes
Contained by
textcrit: app rdgGrp
May contain
analysis: c cl interp interpGrp m pc phr s span spanGrp w
certainty: certainty precision respons
core: abbr add address bibl biblStruct binaryObject cb choice cit corr date del desc distinct ellipsis email emph expan foreign gap gb gloss graphic hi index l label lb lg list listBibl measure measureGrp media mentioned milestone name note noteGrp num orig p pb ptr q quote ref reg rs ruby said sic soCalled sp stage term time title unclear unit
dictionaries: lang oRef pRef
drama: camera caption castList epilogue move performance prologue set sound spGrp tech view
figures: figure formula notatedMusic table
gaiji: g
header: biblFull idno
iso-fs: fLib fs fvLib
linking: ab alt altGrp anchor join joinGrp link linkGrp seg timeline
msdescription: catchwords depth dim dimensions height heraldry locus locusGrp material msDesc objectType origDate origPlace secFol signatures stamp watermark width
namesdates: addName affiliation bloc climate country district eventName forename genName geo geogFeat geogName listEvent listNym listObject listOrg listPerson listPlace listRelation location nameLink objectName offset orgName persName persPronouns placeName population region roleName settlement state surname terrain trait
nets: eTree forest graph listForest tree
spoken: annotationBlock incident kinesic pause shift u vocal writing
tagdocs: att classSpec code constraintSpec dataSpec eg egXML elementSpec gi ident listRef macroSpec moduleSpec outputRendition specDesc specGrp specGrpRef specList tag val
textcrit: app lacunaEnd lacunaStart listApp listWit wit witDetail witEnd witStart
textstructure: argument byline div docAuthor docDate docEdition docImprint docTitle epigraph floatingText imprimatur titlePage titlePart
transcr: addSpan am damage damageSpan delSpan ex fw handShift listTranspose metamark mod redo restore retrace secl space subst substJoin supplied surplus undo
verse: caesura rhyme
character data
Note

The term lemma is used in text criticism to describe the reading given in the main text, which may be used as a heading in the apparatus itself. This usage connects it to mathematics (where a lemma is a proven proposition used as a step in a proof, a "given") and natural-language processing (where a lemma is the dictionary headword associated with an inflected form in the running text).
Example
<app>
 <lem wit="#El #Hg">Experience</lem>
 <rdg wit="#La" type="substantive">Experiment</rdg>
 <rdg wit="#Ra2" type="substantive">Eryment</rdg>
</app>
Content model 
<content>
 <alternate minOccurs="0"
  maxOccurs="unbounded">
  <textNode/>
  <classRef key="model.divLike"/>
  <classRef key="model.divPart"/>
  <elementRef key="titlePage"/>
  <elementRef key="argument"/>
  <elementRef key="byline"/>
  <elementRef key="docAuthor"/>
  <elementRef key="docDate"/>
  <elementRef key="docEdition"/>
  <elementRef key="docImprint"/>
  <elementRef key="docTitle"/>
  <elementRef key="epigraph"/>
  <elementRef key="imprimatur"/>
  <elementRef key="titlePart"/>
  <elementRef key="epilogue"/>
  <elementRef key="performance"/>
  <elementRef key="prologue"/>
  <elementRef key="set"/>
  <classRef key="model.gLike"/>
  <classRef key="model.phrase"/>
  <classRef key="model.inter"/>
  <classRef key="model.global"/>
  <classRef key="model.rdgPart"/>
 </alternate>
</content>
Schema Declaration 
<rng:element name="lem">
 <rng:ref name="att.global.attributes"/>
 <rng:ref name="att.global.rendition.attributes"/>
 <rng:ref name="att.global.linking.attributes"/>
 <rng:ref name="att.global.analytic.attributes"/>
 <rng:ref name="att.global.facs.attributes"/>
 <rng:ref name="att.global.change.attributes"/>
 <rng:ref name="att.global.responsibility.attributes"/>
 <rng:ref name="att.global.source.attributes"/>
 <rng:ref name="att.textCritical.attributes"/>
 <rng:ref name="att.written.attributes"/>
 <rng:ref name="att.witnessed.attributes"/>
 <rng:zeroOrMore>
  <rng:choice>
   <rng:text/>
   <rng:ref name="model.divLike"/>
   <rng:ref name="model.divPart"/>
   <rng:ref name="titlePage"/>
   <rng:ref name="argument"/>
   <rng:ref name="byline"/>
   <rng:ref name="docAuthor"/>
   <rng:ref name="docDate"/>
   <rng:ref name="docEdition"/>
   <rng:ref name="docImprint"/>
   <rng:ref name="docTitle"/>
   <rng:ref name="epigraph"/>
   <rng:ref name="imprimatur"/>
   <rng:ref name="titlePart"/>
   <rng:ref name="epilogue"/>
   <rng:ref name="performance"/>
   <rng:ref name="prologue"/>
   <rng:ref name="set"/>
   <rng:ref name="model.gLike"/>
   <rng:ref name="model.phrase"/>
   <rng:ref name="model.inter"/>
   <rng:ref name="model.global"/>
   <rng:ref name="model.rdgPart"/>
  </rng:choice>
 </rng:zeroOrMore>
</rng:element>
element lem
{
   att.global.attributes,
   att.global.rendition.attributes,
   att.global.linking.attributes,
   att.global.analytic.attributes,
   att.global.facs.attributes,
   att.global.change.attributes,
   att.global.responsibility.attributes,
   att.global.source.attributes,
   att.textCritical.attributes,
   att.written.attributes,
   att.witnessed.attributes,
   (
      text
    | model.divLike
    | model.divPart
    | titlePage
    | argument
    | byline
    | docAuthor
    | docDate
    | docEdition
    | docImprint
    | docTitle
    | epigraph
    | imprimatur
    | titlePart
    | epilogue
    | performance
    | prologue
    | set
    | model.gLike
    | model.phrase
    | model.inter
    | model.global
    | model.rdgPart
   )*
}