<quote>
The text:relative-tab-stop-position attribute specifies whether the position of tab stops is relative to the left margin or to the left indent as determined by the paragraph style.
</quote>

the left margin and the left indent are not necessarily the same, so this should be read as an "exclusive or".
but then the description of the values follows:

<quote>
false: paragraph style does not determine position of tab stops relative to the left margin or left ident.
true: paragraph style determines the position of tab stops relative to the left margin or left ident.
</quote>

now it has become a "logical/inclusive or".
(and ident is missing an "n")