Data item mapping lines, documentation, variables

Fixed issue with data item mapping lines and improved documentation and
variable naming
Revert "Data item mapping lines, documentation, variables"

This reverts commit 3c1a00b0ab9a84a77fe64a2901a12b3ac7638cea.
Revert "Revert "Data item mapping lines, documentation, variables""

This reverts commit 04901bfc45a0c0af98ebb03cc35f09754150f95c.