diff --git a/index.bs b/index.bs
index 3a25850f..6f901f0c 100644
--- a/index.bs
+++ b/index.bs
@@ -763,9 +763,9 @@ NOTE: For a given [=audio_element_type=], a future version of the specification
 - The type SHALL NOT be duplicated in one [=Audio Element OBU=].
 - When [=codec_id=] = <code>fLaC</code> or <code>ipcm</code>, the type PARAMETER_DEFINITION_RECON_GAIN SHALL NOT be present.
 - When [=num_layers=] > 1, the type PARAMETER_DEFINITION_RECON_GAIN SHALL be present.
-- When the highest [=loudspeaker_layout=] of the (non-)scalable channel audio (i.e., [=num_layers=] = 1) is less than or equal to 3.1.2ch, the type PARAMETER_DEFINITION_DEMIXING SHALL NOT be present.
+- When the [=loudspeaker_layout=] = 15 or the [=loudspeaker_layout=] of the (non-)scalable channel audio (i.e., [=num_layers=] = 1) is less than or equal to 3.1.2ch (i.e., Mono, Stereo, or 3.1.2ch), the type PARAMETER_DEFINITION_DEMIXING SHALL NOT be present.
 - When the highest [=loudspeaker_layout=] of the scalable channel audio (i.e., [=num_layers=] > 1) is greater than 3.1.2ch, both PARAMETER_DEFINITION_DEMIXING and PARAMETER_DEFINITION_RECON_GAIN types SHALL be present.
-- When [=num_layers=] = 1 and [=loudspeaker_layout=] is greater than 3.1.2ch, the type PARAMETER_DEFINITION_DEMIXING MAY be present.
+- When [=num_layers=] = 1 and [=loudspeaker_layout=] is greater than 3.1.2ch (i.e., 5.1.2ch, 5.1.4ch, 7.1.2ch, or 7.1.4ch), the type PARAMETER_DEFINITION_DEMIXING MAY be present.
 - An OBU parser SHALL be able to parse [=param_definition_type=] = P (where P > 2) and [=param_definition_size=]. The OBU parser SHOULD ignore the bytes indicated by [=param_definition_size=] that it does not recognize.
 
 <dfn noexport>demixing_info</dfn> is an instance of the [=DemixingParamDefinition()=] class, which provides the parameter definition for the demixing information, which is used to reconstruct a scalable channel audio representation. The corresponding parameter data to be provided in [=Parameter Block OBU=]s with the same [=parameter_block_obu/parameter_id=] is specified in the [=DemixingInfoParameterData()=] class.