A procedure mask is used for performing patient procedures, or when patients are in isolation to protect them from potential contaminants. They are used for 'respiratory etiquette' to prevent people from spreading germs via talking, coughing, or sneezing.
Rolling-wave planning is the process of project planning in waves as the project proceeds and later details become clearer; similar to the techniques used in agile software development approaches like Scrum.. Work to be done in the near term is based on high-level assumptions; also, high-level milestones are set.
A cash balance plan is a defined benefit retirement plan that maintains hypothetical individual employee accounts like a defined contribution plan. The hypothetical nature of the individual accounts was crucial in the early adoption of such plans because it enabled conversion of traditional plans without declaring a plan termination.