Not clearly defined

please, read below, it is pretty well explained

What are the clinical features of erythema multiforme?
Many patients report prodromal symptoms including fatigue, malaise, myalgia, or fever. These likely represent the course of precipitating illness rather than true prodrome.

Cutaneous features
Cutaneous lesions develop at the peripheries before spreading centrally.
Distribution is usually symmetrical with a preference for extensor surfaces.
May be painful, pruritic, or swollen.
Early lesions present as round, erythematous papules which later develop into target lesions.
Target lesions consist of three concentric rings of colour variation:
A central, dusky area of epidermal necrosis
Surrounded by a lighter oedematous area
With a peripheral erythematous margin.
Atypical lesions may be present with typical lesions. Atypical lesions are raised with poorly defined borders and/or fewer zones of colour variation.
In severe disease, up to hundreds of lesions may be present in different developmental stages, at times making it difficult to identify characteristic lesions.