Intention of Single Threader step in Pentaho PDI

Hi Carlos,Thanks for your reply! Sure, I have an example which I attach.There is a simple transformation that has a data grid of first_name and last_name fields and calls a sub-transformation which concatenates them into a full_name field via a single threader step. Before the single threader there is a an Add constants step which adds a constant called project_name which can be seen in the Input Fields of the single threader but not in the Output Fields. Despite this I can copy the project_name field in the Calculator step after the single threader but in the second Calculator step I cannot call up the project_name field, although I can see the project_copy field. I should mention that the first Calculator step had been created when the preceding step was a Simple Mapping call to the same sub-transformation, hence I was able to access the project_name field at that time.

Cheers

Rob