TEST :Syntax Checking for simpleType Declaration : Union with optional attribute id = ''
http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#Simple_Type_Definitions
| Item | Value | 
|---|---|
| title | stE004 - stE004 | 
| name | stE004 | 
| source | ../stE004.xsd | 
| schemaName | ../stE004.xsd | 
| keywords | schema negative | 
| package | javasoft.sqe.tests.simpletype.ste004 |