Locus of the time evolution of 1 − 10 TeV emission in surface brightness and photon index, for our three typical SNR-PWN systems. The top panel results from a calculation without particle escape, and PWN is the only emission component. The bottom panel results from a calculation with particle escape across the system, and gamma-ray emission is contributed by the PWN, SNR, and CSM components. The extent of the CSM component was computed under the assumption of suppressed spatial diffusion, by a factor of 1000 with respect to the average Galactic value, and the SNR and CSM components were grouped together for reasons detailed in the text. Model-predicted emission is compared to data from the HGPS and LHAASO catalogues. Stars indicate the starting point of each track.