How to create a multi-line text box control for processioning script tool

[SurendranNeelakantan]

I am creating a ArcGis 10.5 Desktop processioning python toolbox  to edit  map document properties.  Is there a Multi-line  property for "GPString" datatype?    What is the best  control to edit long text for summary and description text ?  How do I create a multi line text box control for the tool parameter?

[DanPatterson_Retired]

There isn't one.  If this is to provide information to the user, then it should be contained in the metadata/help information

[DanPatterson_Retired]

Unless you are referring to multivalue parameters