Fab rules

All lengths: min_track_width, min_clearance, min_drill, min_via_drill, min_via_diameter, min_annular_ring (vias, microvias use min_microvia_diameter), min_blind_via_drill, min_controlled_depth_drill, min_microvia_drill, max_microvia_drill, min_microvia_diameter, min_hole_to_hole, min_copper_to_edge, min_silk_width, min_silk_text_height, min_mask_web (0.1 mm), max_drill, min_npth_drill, min_plated_slot_width, min_npth_slot_width, min_pth_annular_ring, min_via_hole_to_copper, min_pth_hole_to_copper, min_inner_pth_hole_to_copper, min_npth_to_copper, min_smd_pad_gap, min_hole_to_smd_pad, max_filled_via_drill, min_bga_pad, min_bga_pitch, min_part_to_edge, min_body_to_edge, flex_zone; plus max_aspect_ratio, a plain number (hole depth over drill), max_microvia_aspect_ratio (dielectric depth over laser drill), max_controlled_depth_aspect_ratio (depth over drill of a controlled depth via), and the switches hdi (the fab builds blind, buried and microvias and backdrills) and stacked_microvias (the fab stacks microvias). Footprints are checked against the rules of every board whose layout places them, so a project with a 4 layer and a 2 layer board holds each footprint only to the boards it is on. A footprint no layout places is checked against each board and reported for the one it fits best; with no board, against generic.

The fab preset is a table keyed by the copper layer count, the outer copper weight (from the first copper layer's thickness) and the finish, so a 4 layer 1 oz board gets tighter track rules than a 2 layer 2 oz one. Anything in [rules] overrides the table. The jlcpcb values come from https://jlcpcb.com/capabilities/pcb-capabilities:

Where agentee is stricter than the page, on purpose: min_copper_to_edge stays 0.3 mm (the page allows 0.2 mm on a routed edge, which is milled to +/-0.2 mm, and 0.4 mm on a V-cut), min_hole_to_hole stays 0.5 mm (the page gives 0.45 mm between pad holes and 0.2 mm between vias), and min_hole_to_smd_pad (0.2 mm, the via hole to track figure) and min_part_to_edge (0.5 mm) are agentee's choices, not on the page. min_body_to_edge (1.0 mm) follows assembly DFM guides, which keep every component 1 mm from the board edge for depaneling and handling. flex_zone (5 mm) follows Knowles on MLCC flex cracking: the stress zone is typically within 5 mm of the PCB edge or fixing points.

The generic and jlcpcb presets build through vias only (hdi = false); their microvia and blind via limits (0.1 mm laser drill, 0.3 mm pad, 0.8:1, 0.2 mm blind drill) apply once [rules] hdi = true is set. The hdi preset is generic with PCBWay's published HDI capability table (https://www.pcbway.com/hdi-pcb.html, "HDI PCB Manufacturing Capabilities": builds 1+N+1 to 6+N+6, 0.065/0.065 mm trace and space, 0.15 mm mechanical drill, 4 mil laser drill standard and 8 mil at most on a dielectric of 0.15 mm or less, 0.15 mm controlled depth PTH drill, 14:1 aspect ratio, 4 mil green mask bridge), for the IPC-2226 builds: type I (one microvia layer, 1+N+1), type II (type I with buried vias in the core) and type III (two or more microvia layers, 2+N+2), on the hdi-6l-1n1 and hdi-8l-2n2 stackups. Rules the table does not give keep a named reason:

A 0.07 mm 1080 build-up layer under a 0.1 mm laser drill is 0.7:1, inside the 0.8:1.

max_controlled_depth_aspect_ratio is 1 in every preset, from Sanmina's fab note "Backdrilling and Blind/Buried Via Formation" (https://www.sanmina.com/pdf/solutions/bbf.pdf): blind via formation by controlled depth drilling "is limited by the throw of copper-plating baths to a maximum aspect ratio of 1:1". No published source gives a controlled depth drill for generic or jlcpcb: JLCPCB's capabilities page lists laser blind vias (0.075 to 0.15 mm), mechanical buried vias and backdrilling but no controlled depth drilling. So both presets reject a controlled depth via like any other via but through (hdi = false), and min_controlled_depth_drill there is not a number of its own but their blind via drill (min_blind_via_drill, 0.2 mm), applied once hdi = true; set min_controlled_depth_drill in [rules] from your fab's figure. On hdi-6l-1n1 a 0.15 mm controlled depth drill reaches In1.Cu or In4.Cu (0.123 mm deep), not In2.Cu.