MONDRIAN: Illustrate XML schema format with a skeleton XML doc.

    Indent XML exmaples in schema doc using CSS properties, so
    that they wrap more predictably.

    Add BNF of XML syntax, from which I have generated
    http://clapham.hydromatic.net/mondrian-3.1-bnf/

[git-p4: depot-paths = "//open/mondrian/": change = 12750]

doc/schema.bnf

@@ -0,0 +1,57 @@
+AggExclude ::= "<AggExclude/>" AggFactCount ::= "<AggFactCount/>"
+AggForeignKey ::= "<AggForeignKey/>"
+AggIgnoreColumn ::= "<AggIgnoreColumn/>"
+AggLevel ::= "<AggLevel/>"
+AggMeasure ::= "<AggMeasure/>"
+AggName ::=
+  "<AggName>" AggFactCount (AggIgnoreColumn | AggForeignKey | AggMeasure | AggLevel)* "</AggName>"
+AggPattern ::=
+  "<AggName>" AggFactCount (AggIgnoreColumn | AggForeignKey | AggMeasure | AggLevel)* AggExclude* "</AggName>"
+CalculatedMember ::= "<CalculatedMember>" Formula? CalculatedMemberProperty* "</CalculatedMember>"
+CalculatedMemberProperty ::= "<CalculatedMemberProperty/>"
+Closure ::= "<Closure>" Table "</Closure>"
+Column ::= "<Column>/>"
+ColumnDef ::= "<ColumnDef/>"
+ColumnDefs ::= "<ColumnDefs>" ColumnDef* "</ColumnDefs>"
+ColumnExpression ::= "<ColumnExpression>" SQL* "</ColumnExpression>"
+Cube ::= "<Cube>" Relation (Dimension | DimensionUsage)* Measure* CalculatedMember* NamedSet* "</Cube>"
+CubeGrant ::= "<CubeGrant>" DimensionGrant* HierarchyGrant* "</CubeGrant>"
+CubeUsage ::= "<CubeUsage/>"
+CubeUsages ::= "<CubeUsages>" CubeUsage+ "</CubeUsages>"
+Dimension ::= "<Dimension>" Hierarchy+ "</Dimension>"
+DimensionGrant ::= "<DimensionGrant/>"
+DimensionUsage ::= "<DimensionUsage/>"
+Formula ::= "<Formula>" text "</Formula>"
+Hierarchy ::= "<Hierarchy>" RelationOrJoin? Level+ MemberReaderParameter* "</Hierarchy>"
+HierarchyGrant ::= "<HierarchyGrant>" MemberGrant* "</HierarchyGrant>"
+InlineTable ::= "<InlineTable>" ColumnDefs Rows "</InlineTable>"
+Join ::= "<Join>" RelationOrJoin RelationOrJoin "</Join>"
+KeyExpression ::= "<KeyExpression>" SQL* "</KeyExpression>"
+Level ::= "<Level>" KeyExpression? NameExpression? OrdinalExpression? ParentExpression? Closure? Property+ "</Level>"
+Measure ::= "<Measure>" MeasureExpression? CalculatedMemberProperty* "</Measure>"
+MeasureExpression ::= "<MeasureExpression>" SQL* "</MeasureExpression>"
+MemberGrant ::= "<MemberGrant/>"
+MemberReaderParameter ::= "<MemberReaderParameter/>"
+NamedSet ::= "<NamedSet>" Formula? "</NamedSet>"
+NameExpression ::= "<NameExpression>" SQL* "</NameExpression>"
+OrdinalExpression ::= "<OrdinalExpression>" SQL* "</OrdinalExpression>"
+Parameter ::= "<Parameter/>"
+ParentExpression ::= "<ParentExpression>" SQL* "</ParentExpression>"
+Property ::= "<Property/>"
+Role ::= "<Role>" SchemaGrant* Union? "</Role>"
+RoleUsage ::= "<RoleUsage/>"
+Row ::= "<Row>" Value* "</Row>"
+Rows ::= "<Rows>" Row* "</Rows>"
+Schema ::= "<Schema>" Parameter* Dimension* Cube* VirtualCube* NamedSet* Role* UserDefinedFunction* "</Schema>"
+SchemaGrant ::= "<SchemaGrant>" CubeGrant* "</SchemaGrant>"
+SQL ::= "<SQL>" text "</SQL>"
+Table ::= "<Table>" SQL? AggExclude* (AggName | AggPattern)* "</Table>"
+Union ::= "<Union>" RoleUsage* "</Union>"
+UserDefinedFunction ::= "<UserDefinedFunction/>"
+Value ::= "<Value>" text "</Value>"
+View ::= "<View>" SQL* "</View>"
+VirtualCube ::= "<VirtualCube>"  CubeUsages VirtualCubeDimension* VirtualCubeMeasure* CalculatedMember* NamedSet* "</VirtualCube>"
+VirtualCubeDimension ::= "<VirtualCubeDimension/>"
+VirtualCubeMeasure ::= "<VirtualCubeMeasure/>"
+Relation ::= Table | View | InlineTable
+RelationOrJoin ::= Join | Table | View | InlineTable