The tag is a number designated by the programmer between 0 and 31 used to identify a transfer or for a group of transfers for status queries and sequencing operations.
As it is, though, the code doesn't do anything to make sure that clumsy users or programmer bugs don't cause incorrectly formatted data to be put into the number field.
尽管如此，代码不能确保笨拙的用户或程序员漏洞不会导致未正确格式化的数据放入number字段中。
3
For the individual programmer, the ability to quickly build the system while writing new code has a number of benefits.