Blanket lists of units and operations whose members or participants are deemed to be "in-combat", and thus potentially eligible, can be found in OPNAVNOTE 1650 (for specific units and ships) and in chapter 2, appendix E, of recent SECNAVINST's (for specific operations & ships) though, "Neither service in a combat area nor being awarded the Purple Heart Medal automatically makes a service member eligible...," and specific Sailors and Marines may receive the ribbon in recognition of individual actions or various minor operations.