(By Elena Maslova and Vladimir P. Nedjalkov): "Map 106A displays different ways in which languages encode reciprocal situations, i.e. situations like ‘They love each other’. The reciprocal situation comprises at least two simple situations (e.g., She loves him and He loves her), so one way to encode such a situation is to combine expressions for two simple situations... Apparently, this strategy of encoding reciprocated situations is possible in all languages, although the extent to which such a pattern is conventionalized in grammar and common in actual discourse differs from language to language. However, most languages also have simple or complex reciprocal markers (verbal affixes, pronouns, particles, adverbs, etc.), which, if combined with a verb within one clause, signal that the clause describes a reciprocal situation and not just the situation denoted by this verb, without repeating the verb for each simple situation. For example, English has two pronominal reciprocal markers, each other and one another; and in Kolyma Yukaghir (eastern Siberia), there is one reciprocal marker which is prefixed to the verb stem..."
The WALS chapter uses "reciprocal" both for situations ("reciprocal situations", corresponding to the Grammaticon's "mutual situation") and for constructions. The Grammaticon reserves "reciprocal" for strategies.