Can you elaborate what you mean?
Words break according to the rules in the chosen dictionary for the assigned language, and the hyphenation settings you've set, IF and this is a big if, your fonts are Unicode compliant.
You already know that at least one of your fonts is NOT Unicode compliant, and has a character mapped to the underscore position, so it breaks incorrectly.
I feel like I have a seat-of-the-pants understanding of where ID will break Latin-script text - e.g. at a semicolon, whether or not that semicolon is followed by a space - but I've never seen a canonical list. This is frustrating because there are plenty of places where I'd rather it not break when using a custom-encoding non-Unicode font, but InDesign just won't listen to my pleas.
I often use a GREP style to apply No Break to all non-space characters, but frustratingly, the Adobe Paragraph Composer will still break at a valid slash with No Break applied all around if it "thinks" that doing so would lead to a nice rag. Drives me up the wall. Often, using soft returns and the SIngle-Line Composer is the only way to get your Lao/Khmer/Hindi/Nepali/etc. layout to break correctly.
U mean its better to use single line composer for these languages Lao/Khmer/Hindi/Nepali/etc. ?
I am searching wheather indesign can list out the breaking characters for a word ? I have found underscore and backslash where it breaks the words ? Are there any other than this
What I mean is that: true Unicode fonts ought to be typeset using the World-Ready Paragraph Composer, but if you're using old custom-encoding fonts where the glyph looks like a Lao tone mark or a Devanagari vowel or whatever, but is actually encoded as something else, then it's a little easier to use the Adobe Single-Line Composer.
I know of no such list, unfortunately. I can add to the list:
Any hyphen or dash, except for the Non-Breaking Hyphen
Any colon, semicolon, exclamation point, question mark, or comma, even if not followed by a space
I think any bracket or parenthesis, but I am not at my computer and can't check my memory