There's some info on ad_form_new_p in this thread:
https://openacs.org/bboard/q-and-a-fetch-msg.tcl?msg_id=0006YU
Note that within the -form declaration it's not necessary to continue lines with a backslash at the end. The list declarations can span several lines without a problem - emacs in tcl-mode indents them automatically quite nicely, like this:
{start_date:date,to_sql(sql_date),from_sql(linear_date)
{label "Start"}
{format "YYYY/MM/DD HH12:MI AM"}
{minutes_interval {0 45 15}}
{today}
{help}}
And for the risk of being called a nitpicker again: I'd find it nice if the code was properly indented in the example - currently some of the widget declarations align to the left border but should be indented.
Having inline comments in the example would make it more readable too:
} -edit_data {
# valid request to update an existing record
db_exec_plsql note_update { }
ad_returnredirect "."
ad_script_abort
}