visualization :=
    extension?
    userSource
    (sourceVariable | derivedVariable)+
    graph
    labelFrame+
    container?
    style+
    layerController?

extension :=

userSource :=

 sourceVariable := extension* (format | stringFormat)?
derivedVariable := extension* (format | stringFormat valueMapEntry*)?

format := (affix+ | relabel)?
dateTimeFormat :=
numberFormat := affix?
stringFormat := (affix | relabel+)?
affix :=
relabel :=

valueMapEntry :=

graph := location+ coordinates faceting facetLayout interval

location :=

coordinates :=
faceting := cross layer*
interval := labeling footnotes?
labeling := (format | formatting | footnotes)*
formatting := formatMapping*
formatMapping := format
footnotes := footnoteMapping+
footnoteMapping :=

cross := nest+
nest := variableReference+
variableReference :=

facetLayout := tableLayout facetLevel+ setCellProperties*
tableLayout :=
facetLevel := axis

axis := label? majorTicks
label := descriptionGroup | text+
majorTicks := gridline?
gridline :=

descriptionGroup := description+ text
description :=
text := <text>
paragraph :=

setCellProperties := setMetadata setStyle* setFormat+ union?
setMetadata :=
setStyle :=
setFormat := dateTimeFormat | format | numberFormat | stringFormat+

labelFrame := location+ label paragraph?
container := extension? location+ labelFrame+

style :=

layer :=
layerController :=

union := intersect+
intersect := intersectWhere | where+
intersectWhere :=
where :=