Both ongoing and oneTimeOnly snapshots receive a set of initial data as part of the snapshot response. The initial data is the report of the appropriate resource data and connectivity as it exists at the time the request is processed. The contents of the initial data depend most on the current configuration of the local resources and somewhat on the network configuration. The contents of the initial data also depends on the value of the appnPlusSubareaParm specified in the snapshot request. If the appnPlusSubareaParm value is 0 (appnOnly), the NCPs are not reported separately from the VTAM® host; they are considered part of the VTAM composite node.

The initial data is sent by a set of linked-reply messages; each linked-reply message contains one or more sets of the sequence (vertex 1, vertex 2, endpoint 1), abbreviated as (v1,v2,e1). Vertex 1 represents either the VTAM topology agent host node or an owned NCP node. Vertex 1 optionally contains port information. Vertex 2 represents a contacted node adjacent to the node specified in the associated vertex 1; vertex 2 is optional. If both vertex 1 and vertex 2 are present, endpoint 1 represents the transmission group used for the connection and the logicalLink on the vertex 1 side of the connection. If only vertex 1 is present (no vertex 2), endpoint 1 represents a logicalLink at the vertex 1 node that is not currently being used for a connection. Endpoint 1 is optional.

The first time a node is reported as vertex 1 in a snaLocalTopo snapshot, the full set of attribute data associated with that node is reported; this is referred to as the long form of vertex 1. For subsequent reports of that same node in vertex 1, the attribute data is omitted; this is called the short form of vertex 1.

Each sequence of (v1,v2,e1) can report at most one port, one logicalLink, one transmission group, and two nodes. All resources reported in a single sequence of (v1,v2,e1) are related.

To report other VTAM resources, such as other lines or PUs, VTAM must be repeated as a vertex 1 for each sequence of (v1,v2,e1) until the list of resources is exhausted. When all initial data has been sent, the VTAM topology agent sends one additional linked-reply message; the value in the actionReplyInfo field of this message is '()', an empty set.

If the snaLocalTopo snapshot request is the oneTimeOnly type, the empty set linked-reply is followed by the final snapshot RORS response message. If the snapshot is the ongoing type, no additional messages are sent by the VTAM topology agent until a reportable change occurs to a resource within the scope of the snaLocalTopo snapshot request.