content id

The content id of a registered node can be found out via minetest.get_content_id. The name of a node's content id can be fetched with minetest.get name from content id. In comparison to the node names, the content identifiers are not consistent.

When using vmanip, you work with tables containing numbers for performance reasons. Thus, in comparison to minetest.get_node, you don't use the node name string directly but the content it.