ExtremeWare XOS 11.5 supports only the Summit X450 family of switches and the BlackDiamond 8800 series switch.
show access-list usage acl-slice
Platform Availability
This command is available only on the BlackDiamond 8800 a-series and e-series modules and Summit
X450a and X450e series switches.
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ExtremeWare XOS 11.5 Command Reference Guide