A decision-to-decision path, or DD-Path, is a path of execution (usually through a graph representing a program, such as a flow-chart) that does not include any conditional nodes. That is, it is the path of execution between two decisions.

DD (decision-decision)' path is a path of nodes in a directed graph. A chain is a path in which:

• Initial and terminal nodes are distinct
• All interior nodes have in-degree = 1 and out-degree = 1

A DD-path is a chain in a program graph such that:

• It consists of a single node with in-degree = 0 (initial node)
• It consists of a single node with out-degree = 0 (terminal node)
• It consists of a single node with in-deg ≥ 2 or out-deg ≥ 2
• It consists of a single node with in-deg = 1 and out-deg = 1

It is a maximal chain of length ≥ 1.

MM-Path：在google搜索了半天，也找不到其含义，翻阅历来试卷，全称是Message-Module-Path，查阅论文资料找到一篇文章《一个基于UML协作图的集成测试用例生成方法》，上面提到“方法／消息路径(MM-path)”，应该表述有误。在测试里面，MM-路径是功能性测试和结构性测试的一种混合。

curdir=`pwd`
cd /usr/include
vcase `uname -a` in
Linux*)
   h2ph -a termios.h
   h2ph -a asm/termios.h
   h2ph -a features.h
   h2ph -a asm/termbits.h
   h2ph -a asm/posix_types.h
   h2ph -a asm/ioctls.h
   h2ph -a asm/ioctl.h
   h2ph -a bits/termios.h
   h2ph -a gnu/stubs.h
   h2ph -a linux/posix_types.h
   h2ph -a asm/posix_types_32.h
   h2ph -a linux/stddefs.h
   h2ph -a linux/stddef.h
   h2ph -a linux/compiler.h
;;