讀取當前方法，縮回，搜索值

In order to assign to variable the current values of SNSET/APPRCH, SNSET/RETRCT, SNSET/SEARCH it is necessary to execute a standard DMIS command VALUE/.
Specifically the value are returned by assign using the following syntax:

Command	Description
VALUE/SNSET,APPRCH	Assign the current Approach distance to the variable
VALUE/SNSET,RETRCT	Assign the current Retract distance to the variable
VALUE/SNSET,SEARCH	Assign the current Search distance to the variable

a code example is as follow:

$$Declare Return Variable
DECL/DOUBLE,CurrentValue

$$Return Current Approach
CurrentValue=VALUE/SNSET,APPRCH

$$Return Current Retract
CurrentValue=VALUE/SNSET,RETRCT

$$Return Current Search
CurrentValue=VALUE/SNSET,SEARCH