Clarify filter logic (#1308)

doc/latex/biblatex/biblatex.tex

@@ -3818,8 +3818,16 @@ \subsubsection{The Bibliography}
 
 \valitem{postnote}{name}
 
+
 The postnote is an arbitrary piece of text to be printed after the list of references. This option selects the postnote \prm{name}, as defined with \cmd{defbibnote}. By default, no postnote is printed. The note is printed in the standard text font. It is not affected by \cmd{bibsetup} and \cmd{bibfont} but it may contain its own font declarations. See \secref{use:bib:nts} for details.
 
+\end{optionlist*}
+
+The following options can be used to <filter> the entries printed in the bibliography.
+If several <filtering options> are used, an entry will only be printed if it satisfies all filtering conditions.
+In other words, <filtering options> are connected via a logic \emph{and}.
+
+\begin{optionlist*}
 \intitem[\normalfont\em current section]{section}
 
 Print only entries cited in reference section \prm{integer}. The reference sections are numbered starting at~1. All citations given outside a \env{refsection} environment are assigned to section~0. See \secref{use:bib:sec} for details and \secref{use:use:mlt} for usage examples.