Xml with special character

I created a xml file. some value attribute containt an sql query. In this query, i have a special character '<'

<entity name=\"Filtre\" dataSource=\"dsDB\" query=\" SELECT DocID, 
`custom:iMergeField-<<ReLine>>` AS `custom_iMergeField_ReLine`,
FROM Document ;\">

The first character '<' in "custom:iMergeField-<" give me an error.

How to support a character '<' as value or name of attribute in some xml file?

Thx!