While decoding some files in the binary nodeset file format used in the UA high performance SDK my tool complained about invalid Locale values within LocalizedText. The Locale consisted of Carriage Return + Line Feed + 10 space characters. This happened within "EnumValues" properties. I found out that this invalid Locale value was already this way in the XML NodeSet. Several NodeSets are affected, including the following: Core, DI, ADI, FDI plus probably more.

For example:
In Core (Opc.Ua.NodeSet2.xml), Version="1.04.6" PublicationDate="2020-04-14T00:00:00Z", see line 160ff:
<UAVariable NodeId="i=12169" BrowseName="EnumValues" ParentNodeId="i=120" DataType="i=7594" ValueRank="1" ArrayDimensions="0">
<DisplayName>EnumValues</DisplayName>
...
<EnumValueType>
<Value>1</Value>
<DisplayName>
<Locale>
</Locale>
<Text>Mandatory</Text>
</DisplayName>
<Description>
<Locale>
</Locale>
<Text>The BrowseName must appear in all instances of the type.</Text>
</Description>
</EnumValueType>

Of course one could make this element empty like this <Locale/>, but it should actually be omitted (it is optional according to Opc.Ua.Types.xsd).