If a long option shows an argument as mandatory, then it is mandatory for the equivalent short option also. Similarly for optional arguments.

-l, --list[=FORMAT]

list one or all known charsets and aliases

-k, --known=PAIRS

restrict charsets according to known PAIRS list

-h, --header[=[LN/]NAME]

write table NAME on stdout using LN, then exit

-F, --freeze-tables

write out a C module holding all tables

-T, --find-subsets

report all charsets being subset of others

-C, --copyright

display Copyright and copying conditions

--help

display this help and exit

--version

output version information and exit

-v, --verbose

explain sequence of steps and report progress

-q, --quiet, --silent

inhibit messages about irreversible recodings

-f, --force

force recodings even when not reversible

-t, --touch

touch the recoded files after replacement

-i, --sequence=files

use intermediate files for sequencing passes

--sequence=memory

use memory buffers for sequencing passes

-p, --sequence=pipe

use pipe machinery for sequencing passes

-s, --strict

use strict mappings, even loose characters

-d, --diacritics

convert only diacritics or alike for HTML/LaTeX

-S, --source[=LN]

limit recoding to strings and comments as for LN

-c, --colons

use colons instead of double quotes for diaeresis

-g, --graphics

approximate IBMPC rulers by ASCII graphics

-x, --ignore=CHARSET

ignore CHARSET while choosing a recoding path

Option -l with no FORMAT nor CHARSET list available charsets and surfaces. FORMAT is `decimal', `octal', `hexadecimal' or `full' (or one of `dohf'). Unless DEFAULT_CHARSET is set in environment, CHARSET defaults to the locale dependent encoding, determined by LC_ALL, LC_CTYPE, LANG. With -k, possible before charsets are listed for the given after CHARSET, both being tabular charsets, with PAIRS of the form `BEF1:AFT1,BEF2:AFT2,...' and BEFs and AFTs being codes are given as decimal numbers. LN is some language, it may be `c', `perl' or `po'; `c' is the default.

REQUEST is SUBREQUEST[,SUBREQUEST]...; SUBREQUEST is ENCODING[..ENCODING]... ENCODING is [CHARSET][/[SURFACE]]...; REQUEST often looks like BEFORE..AFTER, with BEFORE and AFTER being charsets. An omitted CHARSET implies the usual charset; an omitted [/SURFACE]... means the implied surfaces for CHARSET; a / with an empty surface name means no surfaces at all. See the manual.

If none of -i and -p are given, presume -p if no FILE, else -i. Each FILE is recoded over itself, destroying the original. If no FILE is specified, then act as a filter and recode stdin to stdout.

info recode

should give you access to the complete manual.