When u insert a call to copy of action, the original 
action is copied in the test. This copied action will be 
nonreusable,independent action.What ever changes u make to 
this it will be independent of original action. To make it 
clear i l give u an example like if u take a xerox copy of 
a sheet, the changes u make to xerox will not effect the 
orginal sheet. Same is this also.

      Call to existing is like a link  to the original.
 The called action will be readonly in the test . If u want 
to make anychanges u have to make to the orginal only that 
will be reflected in the called action.
  Here if u want to call the action it shuld be defined as 
reusable but for call to copy of action it need not be 
reusable.

  hope u understood.. 

By using copy of Action we can call any Action whether it is
a  reusable or non-reusable. and we can edit this called
action based on situation. but this modification will not
effect to original Action.

by Using call Existing Action we can Reusable Actions only.
This called reusable actions are known as External Actions.
This External Actions are readonly, we can not do any
modifications to script.

If any Queries...

nanda.dreddy@gmail.com

Hi Nanda,What u send id ok but i hope it is not possible to 
call a non-reusable action.

non-reusable: is one which u can all in that test and only 
once

Just try the call copy of action..and let me know. 

what i said is 100% correct.

Call to copy :
1.Read and write
2.copy the original action
3.There is memory loss
4.Modifications not reflect original copy
5.we can call any Action whether it is
a reusable or non-reusable

Call to existing:
1.Only write mode
2.Modifications in original action reflecting in called action.
3.There is no memory loss
4.we can reusable actions only.