Yes, Peter You are correct !! 
and thanks for pointing that.
And also Its always recommedned to use the internal functions as they serve the prupose without any performance issue.
Like to get he mskey of the mskeyvalue OutString=uIS_Get(Int iStore, String EntryValue);
and to get the value of a sepcific attribute, we can use the function OutString=uIS_GetValue(25, 0, "MyAttr")
It would be appropriate if I could have mentioned that for other scenarios where we don't have any internal functions that serve the purpose, the custom scripts can be written like mentioned in my previous post.
Hi Naveen,
You can refer to here https://help.sap.com/saphelp_nwidmic71/en/using_functions/dse_internal_functions.htm to know what are the internal functions available
Cheers,
Krishna.