Like Igor Moiseyev, they founded what the world mistook for a folk company but what really required professionally trained dancers.

In addition to the singers and musicians who form the core of the company its production requires scenery and costumes and sometimes dancers and non-singing actors.

"In the Night," Jerome Robbins's suite of nocturnal vignettes, requires dancers with strong dramatic presence.

It used several locations including a highly detailed portrayal of a forest, and required many costumes and dancers.

But it is so padded that it requires strong dancers as Manon and Des Grieux to prevent it from becoming lugubrious.

Some parts of the USA have laws forbidding the exposure of female nipples or even areolas, thus requiring female dancers to cover these with pasties.

The work requires dancers who understand the difference between the special way classical steps are used by Mr. Tudor and the way they may be taught in a classroom.

Spanning 20 Years "Movin' Out" also requires dancers who can act in a more traditional way, at least theoretically.

Vaslav Nijinsky's choreography purposefully contradicted the basic techniques of classical ballet: by requiring dancers to "toe-in" their movements became awkward.

The Los Angeles City Council passed a measure that bans erotic lap dancing by requiring dancers to stay at least six feet from customers.