CM: OA is referring to the VTCs available in EFBs.
There’s a weird and counter-intuitive aspect of selecting just the VTC as the chart instead of the ‘mega’ composite map that ‘stitches’ all the WACs, VNCs and VTCs together.
If you select just the VTC, you can’t ‘zoom in’ to see the large scale insets that provide more detail. However, if you select the ‘mega’ map, it does incorporate the insets.
For example, when I select the current Sydney VTC on the EFB I use, there is no depiction of the vertical dimensions of the YSBK airspace, no matter how far I zoom in. However, if I select the ‘mega’ chart, it does depict “D 1500/SFC” inside the YSBK CTR boundary. I have been caught out by this precise difference.
The lack of education campaign about the Melbourne changes is, sadly, a manifestation of a ‘safety’ authority that has long since been that in name only.