# Modeling asset structures with relationships
Typically, asset resources originate from a maintenance system, and the hierarchical structure from the maintenance system often defines how the asset resources are organized in Cognite Data Fusion (CDF).
The relationships resource type allows you to organize the assets in other structures in addition to the standard hierarchical asset structure.
For example, you can choose to organize the assets by their physical location, where the grouping nodes in the hierarchy are buildings and floors, rather than systems and functions. Another example is to build a graph structure that allows you to navigate assets by mimicking their physical connections through wires or pipes.
In this article:
# Building asset structures
When you build an asset structure, think of the assets as the nodes in the graph or hierarchical structure, and relationships as the edges. The relationship type distinguishes a structure from other existing structures.
Each asset object can have one of these roles:
Grouping node. A logical grouping of function nodes for a particular aspect. For example, the physical grouping of equipment on a building floor.
Function node. The functional location in the system. For example, the function of a pump in a production system.
Item node. A physical item that implements a function node. For example, a physical pump with a unique serial number.
# Modeling asset hierarchies
You can group assets by different aspects. One aspect can be the functional location of the asset. You can, for example, group assets by first their functional role, then the functional roles by the sub-systems they belong to, sub-systems by systems, and systems into plants.
Another aspect may be the asset's physical location, where you, for example, first group assets by the room they are located in, then rooms by the floor they are on, the floors by buildings, and buildings by cities. For example:
# Modeling process flows
You can connect assets to mimick the process flow they are part of, for example, in a piped system where fluid flows between assets through pipes or in an electrical system where power flows between assets through electrical wires.
You can use asset resources to represent all the system's relevant functions, and a relationship type, for example,
flowsTo, to create the connection between the asset objects. For example:
# Modeling moving equipment
Throughout its lifetime, physical equipment can serve different roles in a system. For example, a physical pump can be moved between functional locations to meet the changing capacity needs in a system. You can use relationships to model how physical items (asset = item node) have served under different functional nodes (asset = function node) over time using the relationship's time range properties. For example: