@import ... all

test results: style with @import ... all
User Agent Method
@import '' all; @import "" all; @import url() all; @import url('') all; @import url("") all;
Win Amaya 7.2 - 8.0 no yes yes yes yes
Win Amaya 7.2 - 8.0 (print) no yes yes yes yes
Mac iCab 2.9.1 yes yes yes yes yes
Mac iCab 2.9.1 (print) yes yes yes yes yes
Mac IE 5.0 no no yes no yes
Mac IE 5.0 (print) no no yes no yes
Mac IE 5.2.2 no no yes no yes
Mac IE 5.2.2 (print) ? ? ? ? ?
Win IE 5.0 - 6.0 no no no no no
Win IE 5.5 - 6.0 (print) no no no no no
Linux Konqueror 3.0 yes yes yes yes yes
Linux Konqueror 3.0 (print) yes yes yes yes yes
Mozilla 0.8 - 1.3 yes yes yes yes yes
Mozilla 0.8 - 1.3 (print) yes yes yes yes yes
Netscape 4.x no no no no no
Netscape 4.x (print) no no no no no
Mac OmniWeb 4.1.1 yes yes yes yes yes
Mac OmniWeb 4.1.1 (print) yes yes yes yes yes
Linux Opera 5.0 - 6.12 yes yes yes yes yes
Linux Opera 5.0 - 6.12 (print) yes yes yes yes yes
Linux Opera 5.0 - 6.12 (projection) yes yes yes yes yes
Win Opera 3.62 no no no no no
Win Opera 3.62 (print) no no no no no
Win Opera 4.02 - 7.10 yes yes yes yes yes
Win Opera 4.02 - 7.10 (print) yes yes yes yes yes
Win Opera 4.02 - 7.10 (projection) yes yes yes yes yes
Win Opera 7.10 (small screen) yes yes yes yes yes
Mac Safari v. 64 yes yes yes yes yes
Mac Safari v. 64 (print) ? ? ? ? ?
WebTV 2.6 yes yes yes yes yes
MSN TV 2.8 yes yes yes yes yes
Nokia Mobile Browser 3.0.1 no no no no no
Nokia 6590 yes yes yes yes yes
Openwave 6.0 - 6.2 no yes yes no yes
SonyEricsson P800 yes yes yes yes yes

Note: MSN TV 2.8 only assigns the last imported CSS file within each style element.