diff --git a/doc/spec/hal-spec-properties.xml b/doc/spec/hal-spec-properties.xml
index aacf370..fe6b25d 100644
--- a/doc/spec/hal-spec-properties.xml
+++ b/doc/spec/hal-spec-properties.xml
@@ -4365,6 +4365,218 @@
+
+
+ <literal>alsa.virtual</literal> namespace
+
+
+ Device objects with the capability alsa.virtual
+ represent configured ALSA userspace system device, that can be
+ complex (pre and post processing, plugin, address arguments)
+
+
+
+
+
+ Key (type)
+ Values
+ Mandatory
+ Description
+
+
+
+
+
+ alsa.virtual.device (string)
+
+ Examples: plug:"hw:0,1",
+ bluetooth:/org/bluez/audio/device1
+ Yes
+
+ ALSA description as used to open this virtual device.
+
+
+
+
+ alsa.virtual.device_id (string)
+
+
+ Examples: Automatic conversion of hw:0,1
+ Bluetooth Nokia HS-3W headset
+
+ No
+
+ Textual description of the specific device for a card
+
+
+
+
+ alsa.virtual.device_pcm_class (string)
+
+
+ No
+
+ The PCM class of the device.
+
+
+
+
+ generic
+
+
+ A standard PCM sound device (SND_PCM_CLASS_GENERIC).
+
+
+
+
+ multi
+
+
+ A multichannel device PCM sound device (SND_PCM_CLASS_MULTI) which
+ e.g. contains a generic and a modem device.
+
+
+
+
+ digitizer
+
+
+ A PCM digitizer device (SND_PCM_CLASS_DIGITIZER).
+
+
+
+
+ modem
+
+
+ A PCM modem device (SND_PCM_CLASS_MODEM).
+
+
+
+
+ unknown
+
+
+ The value is 'unknown' if the kernel provide no information about the
+ PCM device class of the device (e.g. the file pcm_class is missing).
+
+
+
+
+ none
+
+
+ The value is 'none' if this there is no PCM class for this device.
+
+
+
+
+ alsa.virtual.originating_device (string)
+
+
+ Yes
+
+ UDI of the device the ALSA device is bound to.
+
+
+
+
+ alsa.virtual.type (string)
+
+
+ Yes
+
+ The type of the stream.
+
+
+
+
+
+ control
+
+
+
+ Stream is control device.
+
+
+
+
+
+ capture
+
+
+
+ Stream is capture device.
+
+
+
+
+
+ playback
+
+
+
+ Stream is playback device.
+
+
+
+
+
+ unknown
+
+
+
+ The type of the device is unknown.
+
+
+
+
+
+ hw_specific
+
+
+
+ This is a hardware specific device (as e.g. from snd_fm801 for Fortemedia FM801
+ PCI Audio). The driver can use it freely for purposes that are not covered by
+ standard ALSA API.
+
+
+
+
+
+ timer
+
+
+
+ Stream is the global ALSA timer device.
+ This means, the device is for all ALSA devices/cards.
+
+
+
+
+
+ sequencer
+
+
+
+ Stream is the global ALSA sequencer device.
+ This means, the device is for all ALSA devices/cards.
+
+
+
+
+
+ unknown
+
+
+
+ Stream is unknown device.
+
+
+
+
+
+
<literal>oss</literal> namespace