TLP is the file format used by Tulip. Only network topology (nodes and edges) is currently supported.

TLP Specification Official TLP Specification (Tulip)

Example

The sample below shows a graph of three nodes and two edges.
(tlp "2.0"
(nodes 0 1 2)
(edge 0 1 0)
(edge 1 0 2)
)

Nodes syntax: (nodes node_id node_id ...)
Edges syntax: (edge edge_id source_id target_id)