First of all, there were no midgets.

The Thirteenth Annual Munchkin Convention turned out to be a roomful of people who love the works of L. Frank Baum, the man who wrote the Oz books. Assembled reporters, who had come expecting to write a Hunter Thompson and the Seven Dwarfs story, muttered darkly to latecomers, "No Midgets! No Midgets!"

At the table in front of the modest meeting room, a panel talked about the King of Gnomes and why he hated eggs. The room was full of three different kinds of people:

The kind of neat old guys like your Uncle Henry, who kept his basement filled up with model trains all year long and would let you run them backwards if you wanted. The best kind of uncle there is.

Mothers who read the same children's books that their children do and tell the stories back and forth with their kids. Not a bad kind of mother to have.

Children precocious enough to have a favorite author at 10 or 11. Almost all of them were girls dressed in very homemade and very nifty costumes to look like characters from arcane Oz books. There are worse kids.

After the panel discussion, there was lunch. After lunch, an auction of books donated to the International Wizard of Oz Club.

"Come on and bid now," said Ray Powel, director of the Pennsylvania-New Jersey branch. "We need the money." And the crowd responded - some of those books went for as much as $15.

"Well, I'll tell you how I got interested," said Ray, a quiet, friendly man. "I had read the books when I was a kid, and then about 20 years ago I was at a farmer's market in Marlton, N.J., or was it, well near there somewhere, and I bou ght a book, "The Giant Horse of Oz." You know, L. Frank Baum wrote over 70 books under seven names. L. Frank Baum is the name he used for the Oz books because he hated his first name, which was Lyman.

"I read that book myself - the one I bought - and, well, I went home to my mother's, who was alive at the time and got all my old books and read them all, and then started collecting.

"And then of all things my wife and I were on vacation in Sarasota, Fla., and we met the wife of the police chief, whose name is Mary Scott, and she told us about the International Wizard of Oz Club, and I joined. And now 13 years later here I am director of the Pennsylvania-New Jersey Branch..."

(The executive secretary of theinternational Oz club lives in Kinderhook, Ill. - when an article about the organization ran in a Chicago paper, he received 50 applications for membership the first week. "You get a magazine, "The Baum Bugle," comes out three times a year, and has critical essays..." all for $5, said Powel.)

There are four girls who want their pictures taken and they are sort of giggling around and teasing each other, as girls do. Like all girls of a certain age, their ages are very important and very much in transition.

Jenni Gwirtz, of Marion, Pa., is "going on 12." Sarah Krall, of Cleveland, Ohio, is "going to be 9." ("I won't say when.") Amy Bladen of Media, Pa., will be 11 "soon." And Nancy Bieder of Kennilworth, N.J., says it is okay to say she is 11 and that's all because her birthday was last week.

Sarah has a crown and a dress that looks like real silk. She is Dorothy after she got to Oz. Nancy is dressed as Scraps, the patchwork girl from another Oz book. She has a few patches drawn on her face: "My sister drew then with her makeup that comes in a pencil." Jenni is dressed as Polychrome, the rainbow's daughter from yet another Oz book. And May is dressed as Glinda who helped Dorothy go home by giving her the silver slippers (ruby in the movie version) you can click three times and they will take you anywhere.

"But the best Oz book is "Scallwagging of Oz,"" Jenni says and laughs, slightly embarrassed. "I like it because it has a character named Jenny Jump."

"I like "Magic in Oz,"" says Sarah. "Please remember to print my name with an "h." Because of the three-inch monkeys. You see it's Ozma's birthday and Dorothy..."

"Doesn't have a present for her," says Nancy, "so she goes in the forest..."

"...and the wizard makes all the monkeys small so they're only three inches," says Amy. "Are you guys telling "Magic of Oz"? How about "Road to Oz," where Dorothy meets the Shaggy Man. You remember?"

There are girls talking about Oz books they have read and the characters they remember. Sarah with an "h" says, "Hey guys, President Carter is going to read about us." And everybody stops talking about Oz in a moment. "What shall we say to him?"

"Well, I don't think you should write this down," says Nancy, "but I went to Germany with my father and he was talking German so I couldn't understand, but he said President Carter's name and everybody started laughing. And I asked him why and he said everybody in Europe laughs whenever you mention our president. So that can't be too good. But don't write it down."

"Well, I think maybe you shouldn't say this either," says Sarah. "Wait, don't write - he should do something about inflation. Because my allowance..." she covers her mouth with her hands.

"But listen, your allowance goes up in inflation," says Nancy. "Even the tooth fairy goes up. I used to get a quarter, now I get 50 cents."

"But it should be a dollar," says Jenni.

"Sure, what's 50 cents nowadays?" says Amy. CAPTION: Picture, Jenni Gwirtz, left, and Sarah Krall at the Munchkin Convention; AP