Technically, I would love seeing the type to be an enumeration - In order to provide a slightly better user experience for STS users, could you do:

    <xsd:simpleType>
        <xsd:union memberTypes=remoteCommand xsd:string"/>
    </xsd:simpleType>

	<xsd:simpleType name="remoteCommand">
		<xsd:restriction base="xsd:token">
			<xsd:enumeration value="ls"/>
			<xsd:enumeration value="get"/>
			<xsd:enumeration value="rm"/>
			<xsd:enumeration value="mget"/>
			<xsd:enumeration value="mv"/>
		</xsd:restriction>
	</xsd:simpleType>