c# XDocument Xsd pattern validation with character $ - validation

Question

I have a problem with c# XDocument XSD validation.
The following file is validated well by Xml Spy, but not by .Net (c#)
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="Simple.xsd">
<Var Name="$Toto"/>
</Root>
Schema
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="Root">
<xs:complexType>
<xs:sequence>
<xs:element name="Var">
<xs:complexType>
<xs:attribute name="Name" type="ST_VariableIdentifier" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:simpleType name="ST_VariableIdentifier">
<xs:restriction base="xs:string">
<xs:pattern value="$[a-z,A-Z]*"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>
An idea?

Answer 1

This should work!
<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="Root">
<xs:complexType>
<xs:sequence>
<xs:element name="Var">
<xs:complexType>
<xs:attribute name="Name" type="ST_VariableIdentifier" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:simpleType name="ST_VariableIdentifier">
<xs:restriction base="xs:string">
<xs:pattern value="[$][a-z,A-Z]*"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>

Answer 2

Just to add to the existing answer. This is actually a known 'bug' in the .Net implementation of the W3C specs (acknowledged here on Connect, but Won't fix).
MSDN provides more information (here), together with the workaround mentioned above.
The System.Xml implementation of the World Wide Web Consortium (W3C)
Recommendations for XML Schemas uses the RegEx class to perform
pattern matching of regular expressions. In some cases, the behavior
recommended by W3C differs from the RegEx class behavior. The
following are the known cases where the System.Xml implementation of
pattern matching differs from the W3C specification:
According to the W3C for XML Schema specification, the dollar sign ($)
should be treated as a regular character. However, the System.Xml
validation interprets a dollar sign in the xs:pattern as an
end-of-line anchor. The possible workaround is to replace $ with [$].
If your pattern is already in brackets, such as [abc$], it is not
necessary to make any changes.