vertical seismic force for asce 7-05

huangyhg

vertical seismic force for asce 7-05
as per 12.14.3.1.2, vertical effect should be considered if sds>=0.125. is that rignt?
but i can't find ths same requirement in ibc 2006, and seems not too much engineer used it.
ibc 2006 section 1613 says to use asce 7-05.
section 1605.4 defines em, as based on requirements in asce7 section 12.4.3, which in turn refers to asce7 section 12.4.2.2.  the same exception for sds <= 0.125 exists there.
thank you.