The Book of Common Prayer allows us flexibility in how we perform certain parts of worship. The rubrics give us direction on what those may be. These are the italicized instructions before certain sections. After the Sanctus ("Holy, Holy, Holy"), the BCP says that the people may stand or kneel. Whenever there are two options in a rubric, either are valid to do. However, the first option is generally the preferred. The Eucharistic Prayer is a holy time. People may feel that kneeling is a more reverent act. With the current BCP, the alternative of standing allows us to participate in a celebratory posture. We are lifting our prayers to God in celebration for the sacrifice that Jesus makes for us. Either position is an act of personal piety and acceptable.