This field is analogous to TXC.DOCFMT'SRC except applies to the interpretation of the dst parameter. See the TXC.DOCFMT'SRC table for possible values. Note that the input and output options are generally independent (see Comments, below). For example, you can input from a file in plain text format and output to a string variable in RTF format. You can also specify the same variable and options for both input and output in order to store the output on top of the input.
Comments
There are a couple of exceptions to the above relating to HTML. First, when src is a web-based HTML document, or a form, then the destination storage medium must be TXFF_STRING. In other words, when using XTEXT as a web browser, there is no real destination. You would normally have the TXF_READONLY flag set in this case anyway, so the question of output may be moot but TXFF_STRING avoids any ambiguity of intent.
The second exception is that when editing files in HTML format (either with the intent of creating actual web documents or simply as simpler alternative to RTF to allow basic formatting such as bold), you must select the TXF_PRINTVIEW option in flags in order to enable the TXC.HFLAGS# options that pertain to the output format options. In contrast, the TXF_FITVIEW option is intended for HTML browsing and only saves using a standard set of output options, ignoring most of the TXC.HFLAGS# bits.
