We can replace the xs:sequence, in which the values are required to be in a particular order, with an unlimited xs:choice which should achieve the desired result.
Try this. Note I have replaced <xs:sequence>
with <xs:choice>
. Note also the attributes which allow as many selections as you want.
<?xml version="1.0" encoding="utf-8"?>
<xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<xs:element name="Task">
<xs:complexType>
<xs:choice minOccurs="0" maxOccurs="unbounded"><!-- Here is the change -->
<xs:element name="GoTo" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="X" type="xs:string" minOccurs="0" />
<xs:element name="Y" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="MoveForward" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Distance" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Rotate" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Degrees" type="xs:string" minOccurs="0" msdata:Ordinal="0" />
</xs:sequence>
<xs:attribute name="Direction" type="xs:string" />
<xs:attribute name="Time" type="xs:string" />
</xs:complexType>
</xs:element>
<xs:element name="SoundRecord" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Time" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="SoundPlayback" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Time" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
<xs:attribute name="StartPosition" type="xs:string" />
</xs:complexType>
</xs:element>
<xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true">
<xs:complexType>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element ref="Task" />
</xs:choice>
</xs:complexType>
</xs:element>
</xs:schema>