Suppressed. This element provides data for processing but it is not rendered in the primary flow of text.

It is possible for multiple indexterms, taken together, to form an illogical index. For example, given the following indexterms:

<indexterm><primary>Extensible Markup Language</primary>
  <see>XML</see></indexterm>
<indexterm><primary>Extensible Markup Language</primary>
  <secondary>definition of</secondary>
</indexterm>

there’s no way to construct a logical index because an entry in the index should never have both a see and other content.

DocBook cannot detect these errors. You will have to rely on an external process to find them.

Common attributes and common linking attributes.

These elements contain see: indexterm (db.indexterm.singular), indexterm (db.indexterm.startofrange).

The following elements occur in see: text, abbrev, accel, acronym, alt, anchor, annotation, application, author, biblioref, citation, citebiblioid, citerefentry, citetitle, classname, code, command, computeroutput, constant, coref, database, date, editor, email, emphasis (db._emphasis), emphasis (db.emphasis), envar, errorcode, errorname, errortext, errortype, exceptionname, filename, firstterm (db._firstterm), firstterm (db.firstterm), footnote, footnoteref, foreignphrase (db._foreignphrase), foreignphrase (db.foreignphrase), function, glossterm (db._glossterm), glossterm (db.glossterm), guibutton, guiicon, guilabel, guimenu, guimenuitem, guisubmenu, hardware, indexterm (db.indexterm.endofrange), indexterm (db.indexterm.singular), indexterm (db.indexterm.startofrange), initializer, inlineequation, inlinemediaobject, interfacename, jobtitle, keycap, keycode, keycombo, keysym, link, literal, markup, menuchoice, methodname, modifier, mousebutton, nonterminal, olink, ooclass, ooexception, oointerface, option, optional, org, orgname, package, parameter, person, personname, phrase (db._phrase), phrase (db.phrase), productname, productnumber, prompt, property, quote (db._quote), quote (db.quote), remark, replaceable, returnvalue, shortcut, subscript, superscript, symbol, systemitem, tag, termdef, token, trademark, type, uri, userinput, varname, wordasword, xref.