missing page_up and page_down from Key Codes

[Old-Black-Dog]

As per title, page_up and page_down keys missing from key code list.
I wanted to remap command+page_down to shift+command+4
The tool got me 99% of the way there (thanks!) but needed to edit json manually to assign to page_down:
"description": "ctrl-pagedown to printscreen",
"manipulators": [
{
"from": {
"key_code": "page_down",
"modifiers": {
"mandatory": [
"left_control"
...