(c)
Or.
This operation allows us to specify alternatives in the pattern.
If the 'I' symbol appears between two characters, then there is a match i f and only i f
either of the characters appears in the text.
(d) Closure.
This operation allows parts of a pattern to be repeated arbitrarily. I f we have the
closure symbol '*', then there is a match if and only if the symbol occurs zero or more
times. I f we have the closure symbol '+', then there is a match i f the symbol occurs
one or more times. Closure will be denoted by placing the * or + symbol after the
character, set, or group to be repeated.
2.2 7064 Grammar
The 7064 command language is formally described by a "grammar", i.e. a set of "production
rules" that concisely describes the set of strings that are valid 7064 command sequences.
The rules consists of: "terminal" symbols like '(', ';', 7064 command names, and digits;
"non-terminal" symbols like <cmd>, <unsigned integer const>, and <trig_cmd>, which are
internal to the grammar, are "metasymbols", which describe the meaning of the productions.
Within production rules, character literals are enclosed i n single quotes " i n order to
distinguish them from metasymbols.
One non-terminal symbol (in this case <cmdlist>) is "distinguished" in the sense that a string
of terminal symbols is a valid 7064 command if there is some way to use the productions to
"derive" that string from the distinguished non-terminal symbol (i.e. <cmdlist>) by replacing
(in any number of steps) a non-terminal by any of the "or" clauses on the right-hand side of
a production for that non-terminal symbol.
B-2
Summary of Contents for 7064
Page 2: ...Racal Instruments...
Page 6: ...I 1 1 1 1 1...
Page 21: ...I 1 I I I I I I I I I 1 1 I I I I I I...
Page 29: ...I I I I I I I I I I I I I I I I I I I...
Page 57: ...1 I I I I I I I I I I I I I I I I I I...
Page 77: ...1...
Page 111: ...0 00 0 00 tI I 4 0 0 I7 r i 6 4 7 4 7 0 T 6 0 0 7 28...
Page 112: ......
Page 113: ...7 30 I I I 1 I I I I I I I I I I I I I I I...
Page 115: ...7 32...
Page 148: ......
Page 164: ...I I I I I I I I I I 1 I I I I I I I I...
Page 176: ...extern char error_msg_lookup unsigned errdes endif ERROR_INCLUDE C 8...