The American National Theater opens on Wednesday, as anyone who hasn't been in Siberia knows, and since "Henry IV, Part 1" is not as well known as, say, "Hamlet" (which opens tonight at the Folger), we gathered a few Interesting Facts from literary manager Davies King.

There are four people named Henry in the play, but it should not be too hard to remember who is who. In those days people were often called by their place of birth rather than a surname, so King Henry is sometimes referred to as "Bolingbroke" or even "Lancaster." Henry Percy is called "Northumberland." Their sons go by nicknames: The king's son is Prince Hal, an informality that suggests the low-life company he keeps, and Henry Percy (Jr.) is Hotspur, which reflects his impatient, quick-to-anger temperament.

The character of Falstaff was originally named Oldcastle, but when some members of that family objected Shakespeare changed it. The Bard himself was aware of the connotations of his own name (shaky spear, i.e., cowardice), and at least one critic suggests that this inspired the punning quality of the name Falstaff (false staff -- get it?).

One character in the play does not speak English, and is not even supplied with any lines in the text. "Lady Mortimer speaks Welsh" is the sole direction. Each new production tackles this problem in its own way, so King slipped over to the Folger Library to peruse the Variorum edition, a massive work produced early in this century that records all the textual variations in Shakespeare's plays. ("Hamlet" alone takes up two volumes, each 600 pages long.) King found a reference to a production by German film director Max Reinhardt and then located in the library the German scholarly journal that contained the Welsh he had used.

With the help of a Welsh textbook, Diana Phillips of the British Embassy and some records, King and actress Jossie De Guzman learned it. Few in the audience will understand the words she uses, but we are assured everyone will know the meaning of what she says.

Some of the numerous epithets flung by Falstaff may sound like gibberish. A "micher" (the word can also be used as a verb) is a truant, as in "shall the blessed sun of heaven prove a micher and eat blackberries?" A bull's "pizzle" is his sexual organ. Hal gets his own licks in with "thou knotty-pated fool" (blockhead), "greasy tallow-ketch" (lump of tallow) and "Manning-tree ox" (literally "a town with a noted cattle market," but used as another way of telling Falstaff he's fat.)

Hotspur refers to a "moldwarp," or mole, and "a deal of skimble-skamble stuff," which means confused. "Shrove-tide" is basically Fat Tuesday, or the day before Lent begins.

The Battle of Shrewsbury (1403) ends the play. Its significance? By defeating the Percys there, Henry IV consolidated his position on the throne and a new order of succession. But that happened in Part 2.