tuxpaint.org:  
Tux Paint is a free, award-winning drawing program for children ages 3 to 12 (for example, preschool and K-6)

What is the logic behind the age range ?  Is it just commonsense or is there anything more to it ? Why not 3 to 15.. 
I am just curious as to how the age range came to be.

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Mohan