TEST :Syntax Checking (id, ref) : Test content: only one is allow (all | choice | sequence), sequence follow by all
http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#cModel_Group_Definitions
| Item | Value | 
|---|---|
| title | groupO018 - groupO018 | 
| name | groupO018 | 
| source | ../groupO018.xsd | 
| schemaName | ../groupO018.xsd | 
| keywords | schema negative | 
| package | javasoft.sqe.tests.group.groupo018 |