You can see it in use on Out-Of-The-Box activity called Work-.Open:

Could you please clarify what do you want exactly ?

This is used to identify the pzInskey of the parent case.

Hi,

Below link might be helpful  for more explanation,

https://collaborate.pega.com/question/difference-between-pxcoverinskey-and-pxcoveredinskey-and-their-relation

For example: 

If we are in child case context ,need to update Parent case properties other than opening a parent using refresh and lock.

Using the smart shape 'Update a case' works for the use case,

pyID: .pxCoverInsKey
Data transform: Created in Parent class mapping child/current pyWorkPage property value to parent context.

As of now i am working with pega 7.2 .but wanted to gain info on that one thats why i asked @Gayatri.

i am currently learning 7.3

and all the contributers thanks all of you it helped 

@MarcLasserre_GCS

Hi Avijit,

pxCoverInsKey is the pzInsKey of the Parent case. The name "Cover" says it is the key of Parent. pxCoverInsKey is available in every child case in order to identify its parent. For every child case, the parent is identified using pxCoverInsKey. 

pxCoveredInsKey: pxCoveredInsKey is the pzInsKey of Child Case. For every Parent case can have multiple child cases, all these pzInkseys of child cases are holded in parent in "pxCoveredInsKey".

pxCoveredInskey can be a List Property as it holds more than One Child Case Identification Key.

Hope, you got the understanding.