# openCypher data model
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The Neptune openCypher engine builds on the same property-graph model as Gremlin. In particular:
+ Every node has one or more labels. If you insert a node without labels, a default label named `vertex` is attached. If you try to delete all of a node's labels, an error is thrown.
+ A relationship is an entity that has exactly one relationship type and that forms a unidirectional connection between two nodes (that is, *from* one of the nodes *to* the other).
+ Both nodes and relationships can have properties, but don't have to. Neptune supports nodes and relationships with zero properties.
+ Neptune does not support metaproperties, which are not included in the openCypher specification either.
+ Properties in your graph can be multi-valued if they were created using Gremlin. That is a node or relationship property can have a set of different values rather than only one. Neptune has extended openCypher semantics to handle multi-valued properties gracefully.

Supported data types are documented in [openCypher data format](bulk-load-tutorial-format-opencypher.md). However, we do not recommend inserting `Array` property values into an openCypher graph at present. Although it is possible to insert an array property value using the bulk loader, the current Neptune openCypher release treats it as a set of multi-valued properties instead of as a single list value.

Below is the list of data types supported in this release:
+ `Bool`
+ `Byte`
+ `Short`
+ `Int` 
+ `Long`
+ `Float` (Includes plus and minus Infinity and NaN, but not INF)
+ `Double` (Includes plus and minus Infinity and NaN, but not INF)
+ `DateTime` 
+ `String`