WdExtensions is a helper Java class for working with dictionaries inside an XSLT map. To apply it, the following namespace has to be added:

<?xml version='1.0'?>
<xsl:stylesheet version="2.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:wdExtensions="java:com.whitedoc.xslt.extensions.WdExtensions"
                exclude-result-prefixes="wdExtensions">

There are several static methods:

1. wdExtensions:getValueFromDictionary (String dictionary Uuid, String columnByUuid, String valueToFind, String columnToFind). 
   It can be used to find a value in the column.
2. wdExtensions:getRecordUuidByValueFromDictionary (String dictionaryUuid, String columnUuid, String valueToFind).
   Can be used to find the UUID of a dictionary record.
3. wdExtensions:createAttachementWithSourceFile()
   Extension uploads the original file to storage, creates an attachment UUID, and returns the UUID as a result. This extension can be used if the created envelope requires the original file. Each repetition of extension will create a new attachment with a new UUID.  
4. wdExtensions:getMailboxUuidByAlias(String mailboxAlias)
   The extension accepts an alias name and returns the mailbox UUID. It can be used to configure recipients in the processing order. Instead of mailboxAlias, it can be the path to the corresponding value in the source document.
5. wdExtensions:findEnvelopeUuidByField (String templateUuid, String fieldName, String fieldValue)
   Extension searches for an exact value in the template field and returns the envelope UUID only if one envelope is found.
6. wdExtensions:chainEnvelope (String envelopeUuid)
   Extension returns the existing chainUuid or creates a new one for the envelope. Can return null if already chained by another mailbox. Must be used for the chainUuid attribute in the envelope.