anchor.diff:  Here, the first annotation at column 4, `JJ` is avalue for a feature *PosValue* of the layer *de.tudarmstadt.ukp.dkpro.core.api.lexmorph.type.pos.POS*. For the two features of the layer *webanno.custom.Sentiment* (*Category* and *Opinion*), the values `abstract` and `negative` are
   presented at column 5 and 6 resp.
   
  -==== Multi-Token Span Annotations and Stacked Annotations
  -
  -Multiple span annotation or stacked annotations on a token/sub-token will have a numbered reference enclosed by brackets as `[N]` where *N* refers to the nth annotation on the layer. Stacked annotations are separated by `|` character.
  +==== Disambiguation IDs
  +
  +Within a single line, an annotation can be uniquely identified by its type and stacking index.
  +However, across lines, annotation cannot be uniquely identified easily. Also, if the exact type
  +of the referenced annotation is not known, an annotation cannot be uniquely identified. For this
  +reason, disambiguation IDs are introduced in potentially problematic cases:
  +
  +* stacked annotations - if multiple annotations of the same type appear in the same line
  +* multi-unit annotations - if an annotations spans multiple tokens or sub-tokens
  +* un-typed slots - if a slot feature has the type `uima.tcas.Annotation` and may thus refer to
  +  any kind of target annotation.
  +
  +The disambiguation ID is attached as a suffix `[N]` to the annotation value. Stacked annotations are separated by `|` character.
   
   .Example: Span layer declaration in file header
   [source,text]
  
positive.code: 1-3.2	13-14	s
  ----
  
  Here, the sub-token `play` is indicated by sentence-token number `1-3.1` and the sub-token `s` is indicated by `1-3.2`. 
  
  ==== Span Annotations
  
  
negative.code: 
  ==== Sentence Representation
  
  Sentence annotations are presented following the text marker `#Text=`, before the token annotations. All text given here is inside the sentence boundaries.
  
  .Example: Original text sections
  [source,text]
  