constant of the form %c, etc...



When solving a differential equation (with ode2 for example); maxima use 
constant names such as %k, etc... I do not really understand the role of 
the % sign. What is the difference between constants marked as %k in 
comparison with just a letter (k). I know that there are some letters 
(i,e for example) where the %i, %e design a specific known constant but 
is there a rule in general.

Olive