Stax Digital Garden

PRS-1001 - Parametric Cut-Sheet Specifications in Markdown Frontmatter

2 min read

Living Document Notice
Published 2026-09-17. The evolving architecture, revisions, and connected notes for this dispatch live in the Stax Digital Garden.

Parametric Cut-Sheet Specifications in Markdown Frontmatter

Parametric Cut-Sheet Specifications in Markdown Frontmatter: Dual-trace Phosphor P4 paper white and P20 amber vector CRT macro showing parametric cut-sheet coordinate grids, millimetric margin bounding boxes, and bleed boundary lines

Physical print production demands rigid dimensional constraints that standard web markdown ignores. When rendering documents for physical imposition, letterpress, or commercial offset printing, margins, bleeds, and stock grammage must be specified deterministically. The Bosun Press subsystem formalizes parametric cut-sheet geometry within structured YAML frontmatter.

The Parametric Print Schema

Rather than burying layout geometry in external CSS stylesheets or proprietary page layout files, Press embeds physical media declarations directly into the document root:

print:
  stock:
    standard: "ISO 216"
    size: "A4"
    dimensions_mm: [210.0, 297.0]
    weight_gsm: 120
    finish: "uncoated_acid_free"
  margins_mm:
    inner: 25.4
    outer: 18.0
    top: 20.0
    bottom: 24.0
  bleed_mm: 3.175
  slug_mm: 10.0
  crop_marks: true
  registration_targets: true

The layout engine interprets these parameters directly in millimetric coordinates, preventing rounding errors caused by non-integer CSS pixel conversions.

Headless Coordinate Conversion

In headless print pipelines, dimensions convert from millimeters to PostScript typographical points (1/72 inch) using exact floating-point factors:

pub struct PrintGeometry {
    pub width_pt: f64,
    pub height_pt: f64,
    pub bleed_pt: f64,
}
 
impl PrintGeometry {
    pub const MM_TO_POINTS: f64 = 72.0 / 25.4;
 
    pub fn from_mm(width_mm: f64, height_mm: f64, bleed_mm: f64) -> Self {
        Self {
            width_pt: width_mm * Self::MM_TO_POINTS,
            height_pt: height_mm * Self::MM_TO_POINTS,
            bleed_pt: bleed_mm * Self::MM_TO_POINTS,
        }
    }
}

By decoupling geometric declarations from vendor-locked desktop publishing interfaces, print specifications remain plain text, version-controlled by git alongside the prose they govern.

  • Directus Target: press
  • Garden Source Reference: MOC - Typography & Physical Print Specifications, MOC - Bosun PKM Tools
  • Garden Source Reference: [PRS-1001 - Parametric Cut-Sheet Specifications in Markdown Frontmatter](PRS-1001 - Parametric Cut-Sheet Specifications in Markdown Frontmatter)

Graph View