The index 
                  entry element represents a single entry in an 
                  
                     index
                     , including all related child entries.
                  
               
               The 
                  
                     ref
                      element can be used to link page number references back to the corresponding location in the document.
                  
               
             
            Usage Example
<index>
    <entry>ABERRANT groups, <ref>429</ref>.</entry>
</index>
    Allowed parents
            entry, 
               index and 
               section
               
            
            Allowed children
            This element may contain text.
            
            This element may contain the following children: abbr, 
               address, 
               annoref, 
               annotation, 
               ssml:break, 
               char, 
               citation, 
               code, 
               d, 
               definition, 
               emph (text variant), 
               emph (phrase variant), 
               entry, 
               expansion, 
               xforms:input, 
               rend:linebreak, 
               ln, 
               m:math, 
               name, 
               note, 
               noteref, 
               num, 
               object (text variant), 
               object (phrase variant), 
               pagebreak, 
               ssml:phoneme (text variant), 
               ssml:phoneme (phrase variant), 
               ssml:prosody (text variant), 
               ssml:prosody (phrase variant), 
               quote, 
               xforms:range, 
               ref, 
               its:ruby, 
               s, 
               ssml:say-as (text variant), 
               ssml:say-as (phrase variant), 
               xforms:secret, 
               sel:select, 
               xforms:select, 
               xforms:select1, 
               span (text variant), 
               span (phrase variant), 
               sub, 
               ssml:sub (text variant), 
               ssml:sub (phrase variant), 
               sup, 
               term, 
               xforms:textarea, 
               time, 
               ssml:token (text variant), 
               ssml:token (phrase variant) and 
               w
               
            
            Content model and additional requirements
            
               optional attributes: 
@about, 
                  
@by, 
                  
@class, 
                  
@content, 
                  
@continuation, 
                  
@datatype, 
                  
@desc, 
                  
@its:dir, 
                  
@its:translate, 
                  
@property, 
                  
@rel, 
                  
@rend:prefix, 
                  
@resource, 
                  
@rev, 
                  
@role, 
                  
@sel:selid, 
                  
@ssml:onlangfailure, 
                  
@typeof, 
                  
@xml:base, 
                  
@xml:id, 
                  
@xml:lang and 
                  
@xml:space 
               one or more of 
                  
                  a choice of either one of the 53 elements: 
abbr, 
address, 
annoref, 
annotation, 
char, 
citation, 
code, 
d, 
definition, 
emph, 
emph, 
expansion, 
its:ruby, 
ln, 
m:math, 
name, 
note, 
noteref, 
num, 
object, 
object, 
pagebreak, 
quote, 
ref, 
rend:linebreak, 
s, 
sel:select, 
span, 
span, 
ssml:break, 
ssml:break, 
ssml:phoneme, 
ssml:phoneme, 
ssml:prosody, 
ssml:prosody, 
ssml:say-as, 
ssml:say-as, 
ssml:sub, 
ssml:sub, 
ssml:token, 
ssml:token, 
sub, 
sup, 
term, 
time, 
w, 
w, 
xforms:input, 
xforms:range, 
xforms:secret, 
xforms:select, 
xforms:select1 or 
xforms:textarea 
                     or text
end of choice 
                  
                
               
               Note that in addition to restrictions presented in the content model  above, 
                  					use of this element must also respect the following requirement:
                  
                     - The 
                        
entry element must neither be empty nor contain only whitespace.
                        
                      
                  
                  Such requirements take precedence over any conflicting statements in the
                     						content model or in the lists above of allowed children and parents.
                  
                
             
            Variants
            This element exists in 4 variants. The other 3  variants are:
            
            Namespace
            http://www.daisy.org/ns/z3998/authoring/