The minimum interval between the leading edges of the start bits of two consecutive characters sent by the terminal to the ICC shall be between 11 and 42 etus as indicated by the value of TC1 returned at the answer to reset. If the value returned in TC1 is N, the ICC shall be able to correctly interpret characters sent by the terminal with a minimum interval between the leading edges of the start bits of two consecutive characters of 11.8 + N etus.
终端发送到IC卡的两个连续字符之间的最小时间间隔为11~42 etu。主要用于控制终端发送字符的速度，不能超过IC卡可接受的速度。这个需要在代码的逻辑控制中体现，接收到ATR之后，通过N值，计算出这个最小时间间隔，控制终端的发送时序。
The minimum interval between the leading edges of the start bits of two consecutive characters sent by ICC to the terminal shall be 11 etus. The terminal shall be able to correctly interpret characters sent by the ICC with a minimum interval between the leading edges of the start bits of two consecutive characters of 10.8 etus.
IC卡发送给终端的两个连续字符之间的最小时间间隔为11etu。即使最小间隔为10.8 etu，终端也应该可以正常处理。相当于对终端提出一个最低指标，主要看控制器是否符合该指标，实际代码中没有体现。
The maximum interval between the leading edges of the start bits of two consecutive characters sent in the same block (the character waiting time, CWT) shall not exceed (2^CWI + 11) etus. The character waiting time integer, CWI shall have a value of 0 to 5, and thus CWT lies in the range 12 to 43 etus. The receiver shall be able to correctly interpret a character having a maximum interval between the leading edge of the start bit of the character and the leading edge of the start bit of the previous character of (CWT + 4) etus.
CWT（字符等待时间）：同一块中两个连续字符起始位下降沿之间的最大时间间隔，不应超过（2^CWI+11）个etu。（CWI的值为TB3低4位，取值范围0~5，因此CWT的最小值为12etu）
主要用于终端接收每个字符时的超时处理，检测IC卡是否没了响应。检测发送一个块的时候，字符之间有没间断时间过长，相当于接收方判定发送方是否发送异常的依据。这个需要在代码的逻辑控制中体现，一般来说7816控制器有相应的寄存器保存该值，以便控制器判断超时错误。
The maximum interval between the leading edge of the start bit of the last character that gave the right to send to the ICC and the leading edge of the start bit of the first character sent by the ICC (the block waiting time, BWT) shall not exceed {(2^BWI * 960) + 11} etus. The block waiting time integer, BWI shall have a value in the range 0 to 4, and thus BWT lies in range 971 to 15371 etus for a D of 1.
The terminal shall be able to correctly interpret the first character of a block sent by the ICC following a time BWT+(D*960) etus.
In general, for values of FI and DI other than 1, BWT is calculated using the formula:
BWT = ( 2^BWI * 960 * (372*D/F) + 11 ) etu.
BWT（块等待时间）：终端发送给IC卡的最后一个字符的起始位下降沿与IC卡发出的第一个字符起始位下降沿之间的最大时间间隔，不应超过{(2^BWI * 960) + 11} etu。（BWI的值为TB3的高4位，取值范围为0~4）
主要用于终端检测IC卡是否没了响应。这个需要在代码的逻辑控制中体现，一般来说7816控制器有相应的寄存器保存该值，以便控制器判断超时错误。
一个已接受块的最后一个字符与一个被传输块的第一个字符之间的延迟至少应为BGT但小于BWT。
For the ICC or terminal, the minimum interval between the leading edges of the start bits of the last received character and the first character sent in the opposite direction (the block guard time, BGT) shall be 22 etus. The ICC or terminal shall be able to correctly interpret a character received within 21 etus timed from the leading edge of the start bit of the last character that is sent to the leading edge of the start bit of the received character.
BGT（块保护时间）：对于终端或IC卡，最后一个接收到的字符的起始位下降沿和在相反方向发送的第一个字符起始位下降沿的最小时间间隔须为22etu。
主要用于控制相反方向两个字符的间隔，相当于两个块之间需要有保护，保证终端和IC卡都能接收到数据。