GNU screen

screen is flexible about flow control. Traditionally, some terminals do flow control in-band, using ^S when they want to stop the flow data and ^Q when they want it to resume. On the other hand, some programs (such as emacs) use those keys for other purposes. If flow control is turned on in screen, ^S will stop screen from sending anything more to your terminal and ^Q will resume. Turning flow control off allows those characters to pass through to your programs. The default setting is “auto”, which attempts to determine if flow control is needed or not. screen is generally pretty good at figuring this out.

• -a - “include all capabilities (with some minor exceptions) in each window's termcap, even if screen must redraw parts of the display in order to implement a function.”
• -A - Resize windows to fit the current terminal. Only effective if screen would otherwise try to resize your terminal to fit the windows.
• -f, -fn, -fa - Respectively, set flow control on, off, or automatic. Same as defflow.
• -O - “selects a more optimal output mode for your terminal rather than true VT100 emulation (only affects auto-margin terminals without 'LP'). This can also be set in your .screenrc by specifying 'OP' in a termcap command.”
• -U - Run screen in UTF-8 mode. screen assumes that it can output UTF-8 (normally it checks locale settings) and sets defutf8 on.

• C-a C-b - (break) Sends a break signal to the current window.
• C-a B - (pow_break) Closes and reopens the terminal and sends a break signal.
• C-a f - (flow) Toggle flow setting between on, off, and auto.
• C-a q - (xon) Sends an XON (^Q) to the current window.
• C-a r - (wrap) Toggle the current window's line-wrap setting.
• C-a S - (xoff) Sends an XOFF (^S) to the current window.
• C-a W - (width) Toggle terminal between 80 and 132 columns.
• C-a Z - (reset) Reset the window's terminal settings to its defaults.
• C-a . - (dumptermcap) Write out a .termcap file.

• allpartial on|off - Global command equivalent to setting partial for all current windows. Default is off.
• altscreen on|off - Enables “alternate screen” support (ti and te termcap settings) for screen windows. Does not change existing windows. Default is off.
• bce [on|off] - Set or toggle background-color-erase setting. “If bce is set to on, all characters cleared by an erase/insert/scroll/clear operation will be displayed in the current background color. Otherwise the default background color is used.” Most noticeable when your terminal's “default” background is different from the current background color, such as an xterm with a background image. [What's the default setting? <PMG>]
• c1 [on|off] - Sets or toggles c1 code processing. If on, characters with the high bit set will be treated as an ESC followed by the corresponding 7-bit character. Default is off.
• charset set - “Change the current character set slot designation and charset mapping. The first four character of set are treated as charset designators while the fifth and sixth character must be in range 0 to 3 and set the GL/GR charset mapping. On every position a '.' may be used to indicate that the corresponding charset/mapping should not be changed (set is padded to six characters internally by appending '.' chars). New windows have BBBB02 as default charset, unless an encoding command is active.” [I don't really understand this. It's obviously terminal charset munging, but I don't get the particulars–I just use UTF-8. <PMG>]
• defbce on|off - Same as bce, but sets the default setting for new windows.
• defbreaktype [tcsendbreak|TIOCSBRK|TCSBRK] - Sets the type of break signal sent via the break or pow_break command. Recommended settings are tcsendbreak and TIOCSBRK. TCSBRK blocks the whole session, but may be the only way to get long breaks. [The man page is somewhat light on detail here. Clarifications appreciated. <PMG>]
• defc1 on|off - Same as c1, but sets the default setting for new windows.
• defcharset [set] - Same as charset, but sets the default setting for new windows.
• defflow on|off|auto [interrupt] - Same as flow, but sets the default setting for new windows.
• defgr on|off - Same as gr, but sets the default setting for new windows.
• defencoding enc - Same as encoding, but sets the default setting for new windows.
• defnonblock on|off|numsecs - Same as nonblock. but sets the default setting for new windows.
• defutf8 on|off - Same as utf8, but sets the default setting for new windows.

terminal (allpartial, altscreen, bce, c1, charset, defbce, defbreaktype, defc1, defcharset, defflow, defgr, defencoding, defnonblock, defutf8, defwrap, dumptermcap, encoding, flow, gr, nonblock, dinfo, partial, printcmd, reset, term, termcap, terminfo, termcapinfo, utf8, wrap, zmodem)