dj.1: -d, -i, -o, fixed descriptions

docs/dj.1

@@ -95,41 +95,42 @@ continue reading until a partial or empty read.
 .B -d
 .RS
 Prints all debug information, user-specified or otherwise, before program
-execution.
+execution. Each invocation increments the debug level of the program.
 .RE
 
 .B -i
 .RS
-Takes a path as an argument to open and use in place of standard input.
+Takes a file path as an argument to open and use as an input.
 .RE
 
 .B -n
 .RS
-Causes dj to exit on two consecutive empty reads instead of one.
+Retries failed reads once more before exiting.
 .RE
 
 .B -o
 .RS
-Does the same as
-.B -i
-but in place of standard output. Dj does not truncate output
-files and instead writes over the bytes in the existing file.
+Takes a file path as an argument to open and use as an output.
 .RE
 
 .B -s
 .RS
 Takes a numeric argument as the number of bytes to skip into the input
-before starting to read.
+before starting to read. If the standard input is used, bytes read to this point
+are discarded.
 .RE
 
 .B -q
 .RS
 Suppresses error messages which print when a read or write is partial or
-empty. When
-.B -q
-is specified twice suppresses diagnostic output entirely.
+empty. Each invocation decrements the debug level of the program.
 .RE
 
+.SH STANDARD INPUT
+
+The standard input shall be used as an input if one or more of the input files
+is “-”.
+
 .SH DIAGNOSTICS
 
 On a partial or empty read, dj prints a diagnostic message (unless the
@@ -177,6 +178,10 @@ Many lowercase options have capitalized variants and vice-versa which can be
 confusing. Capitalized options tend to affect output or are more intense
 versions of lowercase options.
 
+.SH CAVEATS
+
+Output files are not truncated on ouput and are instead overwritten.
+
 .SH RATIONALE
 
 This program was based on the dd(1p) utility as specified in POSIX. While