Explain family rules and how they can be explored across two dimensions.

Answers may vary. Family rules, which underlie all aspects of family system structure, prescribe the rights, duties, and range of appropriate behaviors of members within a family. In general, family rules can be explored across two dimensions: explicit or implicit rules and flexible or rigid rules.
Explicit rules are those rules that family members readily recognize and can articulate. These include expectations for behavior that parents impose on children, both prescribed behavior (e.g., complete your chores) and proscribed behavior (e.g., don't hit your brother), as well as negotiated agreements among members of the executive subsystem (e.g., who manages money) and across subsystems (e.g., elders are expected to spoil their grandchildren).
Implicit rules are different. In general, implicit rules are hidden from family members' awareness, similar to the way in which elements of an individual's personality may be hidden in the subconscious. Being hidden, implicit rules can be difficult to detect without careful observation of behavior that tends to reveal their content. But once revealed, implicit rules showcase their importance.
The explicit and implicit rules found in a family system may be either flexible or rigid, depending on context and time. In tense conflicted situations, family members may monitor what they say and how they behave, such as "Be careful what you say around Mom." However, at other times, speaking freely is acceptable. Flexible rules enable the family system to respond to family stressors as well as to the developmental needs of individual members. Rules that permit the system to respond flexibly are usually optimal.