THE NATIONAL THEATER'S billing this week changes to: "For Colored Girls Who Have Considered Suicide/When the Rainbow Is Enuf."

That title has been throwing a lot of Easterners since March '76, but it first surfaced in San Francisco in December '74.

It stands for all it suggests and much, much more. The theatrical experience accompanying it is as unusual as the title.

Ntozake Shange, 29, calls her work "a choreopoem," a true definition, for what lingers as much as the words are the moving visual images, seven women or, as she suggests, seven characteristics of a woman, whom Shange calls "Lady in Orange," "Lady in Brown," "Lady in Yellow," "Lady in Red," "Lady in Green," "Lady in Purple" and "Lady in Blue." In its published form, print cannot suggest the vivid theatricality it breathes on stage, a melange of moods, music, forms animate and inanimate, and loveliness of colors.

With all respect to Shange, who will be reading Monday night at the Folger and in whose head it all began, one must observe that it took collaboration to turn her words into a theatrical experience.

Shange was born Paulette Williams in Trenton, N.J.; her father was a surgeon, her mother a psychiatric social worker. Two South African friends gave her her Zulu name, and after graduating from Barnard, she headed for the University of Southern California for her master's.

"For Colored Girls . . ." began in that phase of her life, simple readings in the Bacchanal, a small woman's bar near Berkeley in early '74. Dancer Paula Moss joined her, choreographing herself to the words in much the way Mary-Averett Seelye introduced the form to Washington some years ago. Other women joined, and Shange has written in her own purposeful spelling:

"Working in bars was a circumstantial esthetic of poetry in San Francisco from Spec's, an old beat hangout, to 'new' Malvina's, Minnie's Can-Do Club, the Coffee Gallery and the Rippleted. The five of us, five women, proceeded to dance, make poems, make music, make a woman's theater for about 20 patrons . . . We were little raw, self-conscious & eager. Whatever we were discovering in ourselves had been in process among us for almost two years.

"More stable as a source of inspiration and historical continuity was the Women's Studies Program at Sonoma State College, where I worked with J. J. Wilson, Joanna Griffin & Wopo Holup over a three-year span.

"Such joy and excitement I knew in Sonoma, then I would commute back the 60 miles to San Francisco to study dance with Raymond Sawyer, Ed Mock & Halifu. Knowing a woman's mind & spirit had been allowed me, with dance I discovered my body more intimately than I had imagined possible."

"For Colored Girls . . ." gradually developed: "The women's community showed up & we were listed as a 'must see' in the Bay Guardian. Eight days after our last weekend at Minnie's, Paula and I left to drive cross country to New York, to do "the show" as we called it at the Studio Rivbea in New York."

There, instead of the filled boites of California, audiences were small, but in an early one were Shange's sister, Ifa Iyam, and a friend, Osborne, nicknamed Oz, Scott.

A year younger than Shange, Scott, whose father was an Army chaplain, had spent his life on the move from Japan to Germany. In high school at Mount Vernon, N.Y., he did some acting but aimed for Friend's World College as a sociology major. He transferred to Antioch College here and as part of a work-study program became a stage manager at Arena Stage. This changed his career directions and he went on to graduate studies studies at New York University School of the Arts.

Watching the readings and dance of "For Colored Girls" in the East Village loft, Scott saw that striking as the words were, they lacked overall structure. When he made this criticism to Shange, she handed him a thick stack of material. His response was: "Let's make a play."

It was Scott's "play" that opened in a Puerto Rican bar on the Lower East Side. There, at Scott's urgings, Woodie King Jr., of the Henry Street Playhouse's New Federal Theater, and Joe Papp saw the experimental work and decided to nurture it for King's stage. A March production there led to a more elaborate one two months later at the Public.

To a striking degree, this parallels Papp's treatment of "A Chorus Line," which also had grown from personal observations to a smash hit at the Public. Both essentially are mood pieces, both avoid intermissions to preserve their moods and both went uptown to commercial Broadway where, with "A Chorus Line" at the Shubert and "For Colored Girls . . ." at the Booth, Papp productions have ruled Shubert Alley for a full year.

At the Booth, Ming Cho Lee's striking setting captured the aural butterflies visually. On a bare stage of several shapes and levels, he designed an enormous rose against a background of dark velvet and a cyclorama on which Jennifer Tipton's lighting softly breathes the colorings of Shange's words. The materials of Judy Dearing's dresses seem to change texture in the shifting lights. Diana Wharton's music is so evanescent that until the stirring finale one hears it without quite listening. In Shange's words the performance ends:

"i found god in myself

& i loved her/i loved her fiercely"

By accompanying the words with imaginative visions, movement and even silence, Shange and her collaborators have achieved the most striking novelty of current theater.

Behind the simultaneous booking of "For Colored Girls" at the National and "A Chorus Line" at the Kennedy Center Opera House, lies the Papp doctrine of encouraging a stage work to grow, to find its own level without the pressures of rehearsal limitations and opening night deadlines. It's a luxury in the producing world, but neither of these creations could have happened in any other way.