In Terminal, they are:
FS: Control-\ 0x1c (field sep)
GS: Control-] 0x1d (group sep)
RS: Control-^ 0x1e (record sep)
US: Control-_ 0x1f (unit sep)
(These control key equivalents have always been the canonical keystrokes to generate the codes)
But they have to be preceded by a Control-V (like in vi) to be treated as input characters. Control-V is the SYN code (synchronous idle), but has no special meaning in an interactive context, which is presumably why it was chosen.
The full set of control codes (0x00 - 0x1f) and their historical meanings are why Apple added the open/closed Apple keys, eventually the Command key. They wanted a set of keystrokes that were unambiguously distinct from the data stream.
Control-S, e.g., will pause text output in the Terminal (also xterm, etc). This was super useful in the days before scrollback. :) Control-Q to resume (actually flush all the buffered output).
Overloading Control sequences was an unforgivable sin committed by Microsoft.
...if I remember the history correctly, Apple decided that having both open/closed Apple keys was confusing, and having the Apple logo on the keyboard was tacky, so they renamed the key for the Mac, and Susan Kare selected a new glyph, which is a Scandinavian "point of interest" wayfinding symbol.
...as a further aside, Control-N and Control-O are the cause of the bizarre graphical glyphs you sometimes see if you do something silly like cat a binary file. Control-N initiates the character set switch, and Control-O restores it. This can be used to fix your Terminal when things go awry. Most people just close the window, but I hate losing history. :)
0x20 - 0x74, unshifted:
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
0x20 - 0x74, shifted:
!"#$%&'()*→←↑↓/▮123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_◆▒bcde°±▒☃┘┐┌└┼⎺⎻─⎼⎽├┤┴┬│≤≥π≠£·
...works in Firefox. YMMV.
Terminal-charset-quickfix: at shell, type "echo ^O". To get the literal ^O, use Control-V then Control-O.