An integer expression from 0 to 511 to indicate the number of a free data channel. You can then pass commands through the data channel to access the file. The file number must be determined by the FreeFile function immediately before the Open statement.
指定可用数据通道数目的任意整数表达式，其值必须在 0 到 511 之间。您可以通过数据通道传送命令以访问文件。文件编号需要借助 Open 语句之前的 FreeFile 函数来确定。