update trace.md

site/docs/doc/trace.md

@@ -20,9 +20,7 @@
 |             `#cost` | 方法执行耗时                                                       |
 |         `[m <arg>]` | 指定 Class 最大匹配数量，默认值为 50。长格式为`[maxMatch <arg>]`。 |
 
-这里重点要说明的是观察表达式，观察表达式的构成主要由 ognl 表达式组成，所以你可以这样写`"{params,returnObj}"`，只要是一个合法的 ognl 表达式，都能被正常支持。
-
-观察的维度也比较多，主要体现在参数 `advice` 的数据结构上。`Advice` 参数最主要是封装了通知节点的所有信息。
+这里重点要说明的是`条件表达式`，`条件表达式`的构成主要由 ognl 表达式组成，所以你可以这样写`"params[0]<0"`，只要是一个合法的 ognl 表达式，都能被正常支持。
 
 请参考[表达式核心变量](advice-class.md)中关于该节点的描述。
 

site/docs/en/doc/trace.md

@@ -20,9 +20,7 @@ Trace method calling path, and output the time cost for each node in the path.
 |               #cost | time cost                                                                                              |
 |         `[m <arg>]` | Specify the max number of matched Classes, the default value is 50. Long format is `[maxMatch <arg>]`. |
 
-There's one thing worthy noting here is observation expression. The observation expression supports OGNL grammar, for example, you can come up a expression like this `"{params,returnObj}"`. All OGNL expressions are supported as long as they are legal to the grammar.
-
-Thanks for `advice`'s data structure, it is possible to observe from varieties of different angles. Inside `advice` parameter, all necessary information for notification can be found.
+There's one thing worthy noting here is `condition expression`. The `condition expression` supports OGNL grammar, for example, you can come up a expression like this `"params[0]<0"`. All OGNL expressions are supported as long as they are legal to the grammar.
 
 Pls. refer to [core parameters in expression](advice-class.md) for more details.