There are multiple methods to load and save text. The high level functions are available in the editor (TWPCustomRTFEdit). They internally use the low level functions defined in the TWPRTFDataCollection class. It is also possible to load the text of a paragraph (TParagraph.LoadFromStream/String) - which is very useful for table paragraphs since it is possible that multiple paragraph can be loaded into one cell. You can also use the properties AsString and SelectionAsString or the function AsANSIString if you need to work with strings.
The load and save format is modified by "format strings". This are strings which contain a format name (such as "RTF", "HTML", "AUTO" or the respcective reader or writer classname) and optional options, such as "-nobinary" or "-onlybody" which are separated by comma. The function AsANSIString accepts such a format string parameter.
Optionally also available are support units to load and save DocX formatted files.