FAT32 works for both OSes, but has a 4GB size limit per file, so it isn't ideal. However there is a 4GB file size limit. You could use NTFS but you will have to install additional software on the Mac in order to read AND write to the volume. exFAT then is the best option.
The riser duct is a problematic zone due to: -build-ups, alkali infiltration and chemical attack to the steel anchors. Following the general rule, we suggest lining the duct with bricks in the round sections and with castables in the square sections.
Stair riser. A reconstituted flight of stairs with stair risers, from the Chakhil-i-Ghoundi Stupa. A side stair riser depicting an Ichtyo-Centaur, also considered as a Buner relief. A stair riser is the near-vertical element in a set of stairs, forming the space between one step and the next. It is sometimes slightly inclined from the vertical so that its top is closer than its base to the person climbing the stairs.