local book = SILE.require("classes/book");
book:loadPackage("masters")
book:defineMaster({ id = "right", firstContentFrame = "content", frames = {
  content = {left = "22.5mm", right = "100%-15mm", top = "20mm", bottom = "top(footnotes)" },
  runningHead = {left = "left(content)", right = "right(content)", top = "top(content)-8mm", bottom = "top(content)-2mm" },
  footnotes = { left="left(content)", right = "right(content)", height = "0", bottom="100%-15mm"}
}})
book:defineMaster({ id = "left", firstContentFrame = "content", frames = {}})
book:loadPackage("twoside", { oddPageMaster = "right", evenPageMaster = "left" });
book:mirrorMaster("right", "left")
SILE.call("switch-master-one-page", {id="right"})

local book = SILE.require("classes/book");
book:loadPackage("masters")
book:defineMaster({ id = "right", firstContentFrame = "content", frames = {
  content = {left = "22.5mm", right = "100%-15mm", top = "20mm", bottom = "top(footnotes)" },
  runningHead = {left = "left(content)", right = "right(content)", top = "top(content)-8mm", bottom = "top(content)" },
  footnotes = { left="left(content)", right = "right(content)", height = "0", bottom="100%-15mm"}
}})
book:defineMaster({ id = "left", firstContentFrame = "content", frames = {}})
book:loadPackage("twoside", { oddPageMaster = "right", evenPageMaster = "left" });
book:mirrorMaster("right", "left")
SILE.call("switch-master-one-page", {id="right"})

Discard space between heading and content frames
Discard space between heading and content frames
