Is there any significance to the order of reaction participants?

A Rhea reaction is composed of two reaction sides (left and right) which are arbitrarily defined.

For those reactions with a specified direction, the position of the reaction participants with respect to the reaction operator (such as an arrow) reflects their role as substrates or products.

Since Rhea release 90, the participants on each side of the reactions are sorted alphabetically (ascii, case insensitive).