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23th chunk of `less.man`
3aaf592e26f1d03b0aa11ef2fb477451888b3244d3abd7e10000000100000fb6
 printf‐style escape sequence (a % followed by x, X, o, d, etc.).  For example, if LESSBINFMT is "*u[%x]", binary characters  are  displayed  in  underlined
       hexadecimal surrounded by brackets.  The default if no LESSBINFMT is specified is "*s<%02X>".  Warning: the result of expanding the character via LESSBINFMT must be less than 31 characters.

       When  the  character  set  is utf‐8, the LESSUTFBINFMT environment variable acts similarly to LESSBINFMT but it applies to Unicode code points that were successfully decoded but are unsuitable for display (e.g., unas‐
       signed code points).  Its default value is "<U+%04lX>".  Note that LESSUTFBINFMT and LESSBINFMT share their display attribute setting ("*x") so specifying one will affect both; LESSUTFBINFMT is read  after  LESSBINFMT
       so its setting, if any, will have priority.  Problematic octets in a UTF‐8 file (octets of a truncated sequence, octets of a complete but non‐shortest form sequence, invalid octets, and stray trailing octets) are dis‐
       played individually using LESSBINFMT so as to facilitate diagnostic of how the UTF‐8 file is ill‐formed.

PROMPTS
       The -P option allows you to tailor the prompt to your preference.  The string given to the -P option replaces the specified prompt string.  Certain characters in the string are interpreted specially.  The prompt mech‐
       anism is rather complicated to provide flexibility, but the ordinary user need not understand the details of constructing personalized prompt strings.

       A percent sign followed by a single character is expanded according to what the following character is:

       %bX    Replaced  by  the  byte  offset into the current input file.  The b is followed by a single character (shown as X above) which specifies the line whose byte offset is to be used.  If the character is a "t", the
              byte offset of the top line in the display is used, an "m" means use the middle line, a "b" means use the bottom line, a "B" means use the line just after the bottom line, and a "j" means use the "target" line,
              as specified by the -j option.

       %B     Replaced by the size of the current input file.

       %c     Replaced by the column number of the text appearing in the first column of the screen.

       %dX    Replaced by the page number of a line in the input file.  The line to be used is determined by the X, as with the %b option.

       %D     Replaced by the number of pages in the input file, or equivalently, the page number of the last line in the input file.

       %E     Replaced by the name of the editor (from the VISUAL environment variable, or the EDITOR environment variable if VISUAL is not defined).  See the discussion of the LESSEDIT feature below.

       %f     Replaced by the name of the current input file.

       %F     Replaced by the last component of the name of the current input file.

       %g     Replaced by the shell‐escaped name of the current input file.  This is useful when the expanded string will be used in a shell command, such as in LESSEDIT.

       %i     Replaced by the index of the current file in the list of input files.

       %lX    Replaced by the line number of a line in the input file.  The line to be used is determined by the X, as with the %b option.

       %L     Replaced by the line number of the last line in the input file.

       %m     Replaced by the total number of input files.

       %pX    Replaced by the percent into the current input file, based on byte offsets.  The line used is determined by the X as with the %b option.

       %PX    Replaced by the percent into the current input file, based on line numbers.  The line used is determined by the X as with the %b option.

       %s     Same as %B.

       %t     Causes any trailing spaces to be removed.  Usually used at the end of the string, but may appear anywhere.

       %T     Normally expands to the word "file".  However if viewing files via
Title: Less: UTF-8 Error Display and Custom Prompts
Summary
This section details how `less` displays problematic octets in UTF-8 files using `LESSBINFMT` for diagnostics. It then describes the prompt customization features in `less`, controlled by the `-P` option, which allows users to tailor the prompt string. It lists the special characters that can be used in the prompt string to display information such as byte offsets, file size, column number, page number, editor name, file name, file index, line numbers, total number of files, and percentages, relative to the current input. It also covers special prompt flags like '%t' that trims trailing spaces and '%T' which indicates whether the input source is a pipe or a file.