T is a capital letter, or upper case, and t is lower case. T是大写字母,或叫大写字母盘;t是小写字母盘。
Bit-string constants look like regular string constants with a B ( upper or lower case ) immediately before the opening quote ( no intervening whitespace ), e.g., B '1001 '. 位串常量看起来很象在开引号前面有一个B(大写或小写)的普通字符串(它们之间没有空白),比如B'1001'。
Double case : a type case combining upper and lower case. 双连字盘:盛载英文大写和小写字粒的字盘。
Double case : A type case combining upper and lower case. This smallest division on the scale is called the least count. 双连字盘:盛载英文大写和小写字粒的字盘。度盘上最小的刻度为最小读数。
Alternatively, bit-string constants can be specified in hexadecimal notation, using a leading X ( upper or lower case ), e.g., X '1FF '. 另外,位串常量可以用十六进制表示法声明,方法是使用前缀的X(大写或者小写),比如,X'1FF'。