docs: improve esfilter doc

diff --git a/docs/class/filters.md b/docs/class/filters.md
index ad00e6911a1e11d4f299cfc34b2fd00c6e1a2524..ae3849f7ee017da41f496090cbb73d6753a0be9a 100644 (file)
--- a/docs/class/filters.md
+++ b/docs/class/filters.md
@@ -5,8 +5,12 @@ available streams then second and so on.
 
 !['Stream filters'](static/img/doc/streamfiltertab.png)
 
-If any elementary stream is not marked as ignored or exclusive, it is 
-used. If you like to ignore unknown elementary streams, add a rule to 
+If any elementary stream is not marked as ignored, used or exlusive,
+it is used. The implicit use rules are marked as last after all user
+rules. Actions like 'empty' which require to know the used streams must
+not rely on the implicit use rules.
+
+If you like to ignore unknown elementary streams, add a rule to
 the end of grid with the any (not defined) comparisons and with the 
 action ignore.
 

diff --git a/docs/property/action.md b/docs/property/action.md
index a084b367de0dfd7d08ff4776cf1d5f7c8cdcf55c..bd174148d45f044f322dcf3242efde7b4a51f6bf 100644 (file)
--- a/docs/property/action.md
+++ b/docs/property/action.md
@@ -6,5 +6,5 @@ Action              | Description
 **USE**             | Use this elementary stream.
 **ONE\_TIME**       | Use this elementary stream only one time per service type (like video,   audio, subtitles) and language. The first sucessfully compared rule wins. For example, when one AC3 elementary stream is marked to be used with ‘eng’ language and another rule with the ONE\_TIME action was   matched, the new AC3 elementary stream will not be added if the language for new AC3 elementary stream is ‘eng’. Note that the second rule might not have the language filter (column) set.   For the CA filter, this rule means that the new CA elementary stream is added only if another CA is not already used. 
 **EXCLUSIVE**       | Use only this elementary stream. No other elementary streams will be used.
-**EMPTY**           | Add this elementary stream only when no elementary streams are used from previous rules.
+**EMPTY**           | Add this elementary stream only when no elementary streams are used from previous rules. It does not match the implicit USE rules which are added after the user rules.
 **IGNORE**          | Ignore this elementary stream. This stream is not used. Another successfully compared rule with different action may override it.