This promise type assures that a matching value string will be present in the specified node within the XML file. If the existing value string does not exactly match, the default promise is to replace the existing value string, within the specified node. The specified node is determined by body-attributes. The promise object referred to is a literal string of text.

bundle edit_xml example
  "text content to replace existing text, including whitespace, within selected node"

    select_xpath => "/Server/Service/Engine/Host/Alias";

Note that typically only a single value string, within a single selected node, is set in each set_text promise. You may of course have multiple promises that each set a value string.