txtDefinition=The first phase of the {\uldb exposition}{\v 81751}, which establishes the {\uldb tonic}{\v 101048} {\uldb key}{\v 85386} using one or more {\uldb themes}{\v 99088}. When a theme in a {\uldb sonata-form}{\v 96905} {\uldb movement}{\v 151907} is referred to as a \'93primary theme,\'94 this is an abbreviation for \'93primary-area theme,\'94 indicating that the theme first appeared in the primary area.