none 

Statements about this table:
the dx 10 bc2 do not have a premultiplied alpha and it be describe as have explicit alpha
the object with a fourcc of dxt4 do not have a dx 10 name and have a 4:1 compression ratio
the object with a fourcc of dxt3 have a 4:1 compression ratio and do not have premultiplied alpha
the fourcc with a value of dxt4 have no dx 10 name and a compression ratio of 4:1
the fourcc with a value of dxt3 be not alpha premultiplied with a compression ratio of 4:1
bc2 be describe as explicit alpha with no alpha premultiplied
dx 10 name bc2 have a no alpha premultiplied and a description of interpolated alpha
bc2 have the same texture type as dxt1
fourcc
dx 10 name
description
alpha premultiplied
dxt1
bc1
1 - bit alpha / opaque
n / a
dxt2
(none)
explicit alpha
yes
dxt3
bc2
explicit alpha
no
dxt4
(none)
interpolated alpha
yes
dxt5
bc3
interpolated alpha
no
fourcc
compression ratio
texture type
dxt1
6:1 (for 24 bit source image)
simple non - alpha
dxt2
4:1
sharp alpha
dxt3
4:1
sharp alpha
dxt4
4:1
gradient alpha
dxt5
4:1
gradient alpha