Version 1.8 of the NV-CONTROL X Extension introduced targettypes for setting and querying attributes as well as receivingevent notification on targets. Targets are objects like X Screens,GPUs and Quadro Sync devices. Previously, all attributes weredescribed relative to an X Screen. These new bits of information(target type and target id) were packed in a non-compatible way inthe protocol stream such that addressing X Screen 1 or higher wouldgenerate an X protocol error when mixing NV-CONTROL client andserver versions.