"Vietnam Memorial," an independently produced documentary to be shown as this week's edition of the PBS "Frontline" series, may aspire to be the definitive filmed account of the opening of, and public reaction to, the Vietnam Veterans Memorial, but the one-hour film serves more as an amendment to superb footage already aired on "The CBS Evening News," "CBS News Sunday Morning," and other network newscasts.

Washington filmmakers Steve York and Foster Wiley shot their documentary--airing at 8 tonight on Channel 26--on film, not tape, and recorded many poignant, anguished encounters among those who visited the memorial in the first weeks after it was dedicated last November. No matter how many similar scenes of hugging, and sobbing, and contemplation one has seen previously, those in this program strike home movingly.

But before the film gets around to the subject of human beings, it must square off yet again with The Issues, issues already lavishly explored elsewhere. These include American guilt not only over the war but over the way the nation received the veterans who had fought in it; the use of the chemical Agent Orange and the aftereffects it may have caused; and other topics. For a while, there is so much accusatory shouting that the program seems designed to uphold the PBS tradition of befouling patriotic holidays with hostile rhetoric. The first few minutes of the film give the impression that only blacks and Hispanics fought in Vietnam.

There is nothing unimportant about the matters being discussed, but the film does not seem the ideal platform for them. Perhaps if it had opened with scenes at the memorial, then digressed to explore the scars still unhealed, the effect would have not been so jarring. As it is now organized, the documentary seems like two different half-hours joined awkwardly at the spine.

Secretary of Defense Caspar Weinberger is heard calling Vietnam "a painful war that we've tried to forget" in Veterans Day ceremonies shown near the beginning of the film. Later, there are excerpts from another ceremony held at Constitution Hall with James Stewart as the master of ceremonies and, of all people, Wayne Newton among the entertainers.

When the film leaves this gathering and retreats to a smaller assemblage of veterans listening to amateur folk singers do Simon and Garfunkel's "Homeward Bound," and the camera explores the polyglot mural of American faces listening to the song, the film turns its corner, and, with the help of background music from "Chariots of Fire," among other sources, soon becomes a heartfelt and stirring expression of loss, sorrow, hope, and finally, reconciliation.