Gas Transposers are blocks capable of either inserting gases into items or extracting gases from items. They therefore have two modes.
Insert Mode: Items can be inserted in the left item slot of the Gas Transposer. You must supply the block with insertable gases using piping or by placing a Gas Source next to the block. When a gas is received, the Gas Transposer will insert the gas into the input and yield it as output placed in the right item slot.
Extract Mode: Items can be inserted in the right item slot of the Gas Transposer. The block will begin extracting the gas from the input. When finished, the gas will be emitted from the front side of the block. If this fails, the block will delay the extraction until it can be completed. Output items are placed in the left item slot.
By using Hoppers, items can be inserted into the input item slot of the current mode through any side other than the bottom. Items in the output item slot of the current mode can be extracted through the bottom.