[media] V4L2 spec: document control events
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil
Mauro Carvalho Chehab
parent
ce7275747b
commit
85724983c4
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@ -79,6 +79,13 @@
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<entry>Event data for event V4L2_EVENT_VSYNC.
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</entry>
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</row>
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<row>
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<entry></entry>
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<entry>&v4l2-event-ctrl;</entry>
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<entry><structfield>ctrl</structfield></entry>
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<entry>Event data for event V4L2_EVENT_CTRL.
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</entry>
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</row>
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<row>
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<entry></entry>
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<entry>__u8</entry>
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@ -109,9 +116,17 @@
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<entry></entry>
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<entry>Event timestamp.</entry>
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</row>
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<row>
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<entry>u32</entry>
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<entry><structfield>id</structfield></entry>
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<entry></entry>
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<entry>The ID associated with the event source. If the event does not
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have an associated ID (this depends on the event type), then this
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is 0.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[9]</entry>
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<entry><structfield>reserved</structfield>[8]</entry>
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<entry></entry>
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<entry>Reserved for future extensions. Drivers must set
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the array to zero.</entry>
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@ -64,7 +64,19 @@
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[7]</entry>
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<entry><structfield>id</structfield></entry>
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<entry>ID of the event source. If there is no ID associated with
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the event source, then set this to 0. Whether or not an event
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needs an ID depends on the event type.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>flags</structfield></entry>
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<entry>Event flags, see <xref linkend="event-flags" />.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[5]</entry>
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<entry>Reserved for future extensions. Drivers and applications
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must set the array to zero.</entry>
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</row>
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@ -99,6 +111,23 @@
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when the last of the MPEG stream has been decoded.
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</entry>
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</row>
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<row>
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<entry><constant>V4L2_EVENT_CTRL</constant></entry>
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<entry>3</entry>
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<entry>This event requires that the <structfield>id</structfield>
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matches the control ID from which you want to receive events.
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This event is triggered if the control's value changes, if a
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button control is pressed or if the control's flags change.
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This event has &v4l2-event-ctrl; associated with it. This struct
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contains much of the same information as &v4l2-queryctrl; and
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&v4l2-control;.
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If the event is generated due to a call to &VIDIOC-S-CTRL; or
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&VIDIOC-S-EXT-CTRLS;, then the event will not be sent to
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the file handle that called the ioctl function. This prevents
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nasty feedback loops.
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</entry>
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</row>
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<row>
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<entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
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<entry>0x08000000</entry>
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@ -108,6 +137,23 @@
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</tgroup>
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</table>
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<table pgwide="1" frame="none" id="event-flags">
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<title>Event Flags</title>
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<tgroup cols="3">
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&cs-def;
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_EVENT_SUB_FL_SEND_INITIAL</constant></entry>
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<entry>0x0001</entry>
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<entry>When this event is subscribed an initial event will be sent
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containing the current status. This only makes sense for events
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that are triggered by a status change. Other events will ignore
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this flag.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="v4l2-event-vsync">
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<title>struct <structname>v4l2_event_vsync</structname></title>
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<tgroup cols="3">
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@ -122,6 +168,100 @@
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="v4l2-event-ctrl">
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<title>struct <structname>v4l2_event_ctrl</structname></title>
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<tgroup cols="4">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>changes</structfield></entry>
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<entry></entry>
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<entry>A bitmask that tells what has changed. See <xref linkend="changes-flags" />.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>type</structfield></entry>
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<entry></entry>
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<entry>The type of the control. See &v4l2-ctrl-type;.</entry>
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</row>
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<row>
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<entry>union (anonymous)</entry>
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<entry></entry>
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<entry></entry>
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<entry></entry>
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</row>
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<row>
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<entry></entry>
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<entry>__s32</entry>
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<entry><structfield>value</structfield></entry>
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<entry>The 32-bit value of the control for 32-bit control types.
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This is 0 for string controls since the value of a string
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cannot be passed using &VIDIOC-DQEVENT;.</entry>
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</row>
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<row>
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<entry></entry>
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<entry>__s64</entry>
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<entry><structfield>value64</structfield></entry>
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<entry>The 64-bit value of the control for 64-bit control types.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>flags</structfield></entry>
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<entry></entry>
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<entry>The control flags. See <xref linkend="control-flags" />.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>minimum</structfield></entry>
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<entry></entry>
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<entry>The minimum value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>maximum</structfield></entry>
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<entry></entry>
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<entry>The maximum value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>step</structfield></entry>
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<entry></entry>
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<entry>The step value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>default_value</structfield></entry>
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<entry></entry>
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<entry>The default value value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table pgwide="1" frame="none" id="changes-flags">
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<title>Changes</title>
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<tgroup cols="3">
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&cs-def;
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_EVENT_CTRL_CH_VALUE</constant></entry>
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<entry>0x0001</entry>
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<entry>This control event was triggered because the value of the control
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changed. Special case: if a button control is pressed, then this
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event is sent as well, even though there is not explicit value
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associated with a button control.</entry>
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</row>
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<row>
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<entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry>
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<entry>0x0002</entry>
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<entry>This control event was triggered because the control flags
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changed.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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</refentry>
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<!--
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