Bahro symbol
From MYSTlore
A Bahro symbol is the only known way to reliably communicate with the Bahro. The symbol is a very simple, graphical representation of an action that the drawer wishes a Bahro to perform. Several Bahro symbols were used quite successfully by The Stranger to prompt the Bahro to manipulate the environment, move a link-in point, and even sing (see Myst V: End of Ages).
The only recent example of communication with a Bahro via a drawn symbol is when Willow Engberg apparently prompted a Bahro to bring her water by drawing the Bahro symbol for "rain." However, given the Bahro's initial reaction to the drawing, and the length of time passed before Willow was given water, it remains unclear that her drawing alone is what spurred the Bahro into action.
