1）pair 名称：
Allegro菜单点击logic-->Assign differential pair，在net filter 中选择所要设的net1,net2, 或直接在board file 中点选net,在Rule Name 中key 入pair 名称﹐点右下方的Add 后会自动增加到上方的Rule Selection Area 中﹐可以点Modify或Delete 来修改或删除所设的pair.
2）设置差分线规则类型
给pair 定义一个net spacing type property(规则类型),如CLK-CLK：点Attach property, net...,注意find 窗口中选property 而非net,再点more...,从左边选取先前设的pair,如CK0R-CK0R,点apply﹐ 在弹出的对话框中点net_spacing_type﹐在右边的value 值中输入CLK-CLK。
3）设置差分线规则参数
set net spacing constrains values , 设定走线线距规则参数值：点constraints 窗口的spacing rule set 下的set values,在出现的对话框中右边空格输入CLK-CLK, 点add 增加到constraint set name 栏。然后按guideline 设定各项spacing.¯ line to line 指的是此对pair 和其它线的间距。
注1： Length Tolerance indicates the amount of tolerance allowed between the total length or delay of the two nets. (两net 之间的误差范围)
注2：Primary Max Sep indicates the maximum edge to edge spacing between a differential pair. (指该pair 本身的间距)
注3：Secondary Max Sep indicates an edge to edge spacing that is greater that the Primary Max Sep value. This allows an increase in thespacing between the differential pair when necessary. The total amount of etch/conductor on a net can not exceed this amount.(必要时允许增大该pair 本身的间距到此值)
