Second post in this DCMA walkthrough, and it's the one that catches schedulers off guard the most: a lead. Not because the math is complicated — it's the opposite, one negative number — but because most people have used one without knowing it had a name, let alone that DCMA wants it gone entirely.
What a lead actually is
Every logic link between two activities can carry a lag — extra time tacked onto the relationship. A positive lag is a wait: "start 3 days after this finishes." A lead is the opposite, a negative lag: "start 3 days before this finishes." Say "Install Rebar" has a Finish-to-Start link to "Pour Concrete" with a 2-day lead. The schedule is telling P6 that concrete can start two days before rebar is actually done.
Why that quietly breaks your logic
A lead doesn't throw an error. The schedule still calculates, dates still populate, the Gantt still looks normal. What it actually does is let two activities overlap in a way the logic link is supposed to prevent — the whole point of a Finish-to-Start relationship is that the successor waits for the predecessor. A lead reintroduces that overlap through the back door, and it drags your float calculations along with it: an activity's float is only meaningful if the logic driving it is real, and a negative lag means part of that logic isn't holding the line it claims to hold.
Why DCMA sets the bar at zero
Unlike most of the DCMA's 14 checks, which allow some tolerance — 5% here, 44 days there — leads get a flat target: 0%. Not "keep it under a threshold." None. DCMA's own reasoning is straightforward: if two activities are genuinely meant to overlap, model that overlap honestly — as a Start-to-Start relationship, or as two separate real activities — instead of hiding it inside a negative number on a Finish-to-Start link that's supposed to mean "wait."
What Ordo7 checks today
In the interest of being exact: Ordo7's engine doesn't automate a Leads check yet. It automates Logic (Check 1), Hard Constraints, High Float, Negative Float, High Duration, and Invalid Dates, plus out-of-sequence progress detection — Leads isn't in that list today. I'm explaining the concept here because it's DCMA Check 2 and it's worth understanding on its own terms, not because Ordo7 is flagging it in your file yet.
Read the full 14-point breakdown, including exactly where Ordo7's coverage stands today, in the DCMA 14-point check guide. Next in this series: Lags — the built-in waiting periods DCMA actually tolerates, up to a point.
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