What are core members?

Some articles on core members, members:

Types of Open Relationships
... may change at any time and tend to contain three types of participants core members, associated members, and affiliated members ... Core members are those participants who have been sexually intimate with several others associated members are those who are involved sexually with ... In a closed group, all participants are core members ...

Famous quotes containing the words members and/or core:

    Jesus, Buddha, Mahommed, great as each may be, their highest comfort given to the sorrowful is a cordial introduction into another’s woe. Sorrow’s the great community in which all men born of woman are members at one time or another.
    Sean O’Casey (1884–1964)

    The ideal of men and women sharing equally in parenting and working is a vision still. What would it be like if women and men were less different from each other, if our worlds were not so foreign? A male friend who shares daily parenting told me that he knows at his very core what his wife’s loving for their daughter feels like, and that this knowing creates a stronger bond between them.
    —Anonymous Mother. Ourselves and Our Children, by Boston Women’s Health Book Collective, ch. 6 (1978)