[gentoo-user] eix output and libpng

Hi,

Blender wants libpng-1.2 and libpng-1.5 seems to be more recent. I
forced the installation of version 1.2.49 for test purposes.

If I do a 

    eix libpng 

I get (beside other things):

    [I] media-libs/libpng
        Available versions:  
        (1.2)	1.2.49 ~1.2.50
        (0)	1.5.10 ~1.5.11 ~1.5.12
        {apng neon static-libs}
        Installed versions:  1.2.49(1.2)(04:53:36 07/20/12) 1.5.10(01:18:39 04/09/12)(apng -neon -static-libs)
        Homepage:            http://www.libpng.org/
        Description:         Portable Network Graphics library

What is the meaning of
        (1.2)	1.2.49 ~1.2.50
        (0)	1.5.10 ~1.5.11 ~1.5.12

in the above output (specifically the '(1.2)' and (0)')?


Thank you very much in advance for any help!

Best regards,
mcc