0-9 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A time mark that is accurately known with respect to an accepted reference time standard. (188) Note: Current uncertainty among international standards is approximately 1 part in 1014 as of 1995.