When using Notes Migrator for SharePoint to migrate Notes rich text documents to SharePoint, you usually let the tool do all the work for you.  Typically, you would tell the tool to extract your rich text "Body" item as HTML and map that to a SharePoint "Note" field (a.k.a. an multi-line text field supporting Enhanced HTML).  In fact you do not even need to do that much as this is the default when you use our built-in data definitions.

But sometimes you want to take more control of how your HTML is encoded.  Most people don't realize that Notes Migrator for SharePoint supports the use of "pass through" HTML.  If you want some string in your source data definition to be interpreted as pure HTML (that is, you don't want it to be escaped as a string in the resulting SharePoint rich text field), then you need to set the Return Type to “HtmlString".

There are two main cases where this is useful:

1. Some custom Notes applications, especially web-enabled Domino applications, actually store raw HTML in text fields.  Using the HtmlString return type is the only way to migrate those to SharePoint rich text fields "as is".
2. Sometime you want to write a formula that actually emits HTML.  This is a nice way to format a rich text presentation of your Notes data in SharePoint.

As an example of the second case, consider this formula in a source data definition column which concatenates two Notes items with a little formatting:

In the preview, we can see that we are generating HTML:

And after mapping this to a SharePoint rich text field, you can see that we have a nicely formatted result:

Note that there is a similar capability available when generating InfoPath XML documents from Notes documents.  You can use the attribute encode="xml" inside your <ppm:replace> tags to indicate that you want the mapped source column to be treated as "pass through" XML.