As I look at different sites, I'm seeing the format has changed.
Well, it is a bit complicated.
I have never seen a manual called "The Samuel French Manual" or anything similar, and I once spent a lot of time making several attempts to track it down over a couple of years.
However, there
is a manual available from Samuel French called "Professional Playscript Format Guidelines & Sample, 2nd Edition" by Mollie Ann Meserve. I bought it a couple of years ago. I think this is probably the quasi-mythical Samuel French format guidelines manual.
It presents a format that should be acceptable to any theater or contest. In fact, if you go through a recent Writers' Market, you usually do not see many references to format in the rules for submission.
Earlier this year the Dramatists Guild of America, in conjunction with Final Draft, put out a new template for stage plays. The only significant differences between it and the more traditional templates are that the DG template:
1. Gives its blessing to the use of a non-Courier font like Times.
2. Uses Action paragraphs that are not Parentheticals, as in the past, but instead are blocks of text indented a few spaces past where the Character Name appears. (If Character is at 4" from the left paper edge, Action starts at about 4.5".) Parentheses are not used for Action. Parentheticals are still used for individual character descriptions and actions, just as in screenplay format.
3. Adopts the screenplay method of using ALL CAPS only for the first appearance of a character. More traditionally, stage plays have capitalized all instances of a character name.
My own thoughts on all of this are:
1. Courier still works best if you use Final Draft, because at least in the Windows operating system FD does not handle proportional fonts (non-Courier fonts) very well. The letter spacing is abnormal, with too much space between some of the letters.
2. I really like the handling of Action. It provides more white space on the page (at the left) and gets the Action out of the way of the dialogue flow on the page. Louis E. Catron was recommending this format many years ago in his excellent book
Playwriting.
3. I still prefer all-caps all the time for appearances of characters, not just the first appearance. However, this is not really an important issue. I doubt anyone really cares.

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