The access-list command is used in order to permit or deny the traffic passing through the PIX.
You can also implement time-based access-lists on the PIX firewall.
Implementation of time-based Access Control Lists (ACLs) is required on the PIX Firewall, so that ACLs can be enabled or disabled for a specific period of time. This capability provides robustness and the flexibility to define access control policies that either permit or deny certain kinds of traffic.
Note: The time-based ACL feature is not supported on PIX devices that run 6.x code and earlier. This feature is introduced in PIX 7.x code.
The access-list and access-group commands are used in order to create ACLs that can be used to permit or deny inbound or outbound connections through the PIX. ACLs are allowed to filter based upon source and destination addressing and ports and are applied individually to each interface that allow for much more granular and secure control of connections, which pass through the PIX.
In order to implement a time-based access list, use the time-range command in order to define specific times of the day and week.
Refer to these documents for more information and implementation details: