I created the specific image file. The diagram is based on Figure 1 of RFC 3320. The copyright statement in RFC 3320 contains the following provisions, which apply to derived works:

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The image is a box diagram explaining w:Signaling Compression. In the top of the diagram is the local application, drawn as one box. In the bottom is the transport layer, drawn as another box. In the middle of the is drawn a third box, this one is white, which contains several other boxes. Messages going one way from one box to another are shown with labeled arrows going in one direction, whereas messages going both ways are shown with bidirectional arrows without labels.

The Local Application sends Application Message and Compartment Identifier to the  Compressor Dispatcher which communicate with two compressors and sends a Sigcomp Message to the Transport Layer.

Another Sigcomp Message comes from the Transport Layer to the Decompression Dispatcher which communicates with the Decompressor (labeled Universal Decompressor Virtual Machine). The Local Application sends a Compartment Identifier to the Decompression Dispatcher and gets a Decompressed Message from it. The compressors communicate with the states in the state handler and the Decompressor be communicates with the state handler which contains them.

I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.