Baselines

Baseline vs Current

This page covers one comparison: the baseline snapshot against the current schedule. It does not cover variance reporting, SPI, or Earned Schedule.

What a baseline is

Snapshot, not Planned Start. The muted bar is the assigned baseline. Planned Start lives on the current activity.

Oracle: a baseline is a copy, or snapshot, of project data at a given time — a static benchmark. You can create many. Only four are used at once to display and compare: the Project Baseline plus the user’s Primary / Secondary / Tertiary. Summarized pages compare against the Project Baseline only. There is one Project Baseline at a time.

You create one by saving a copy of the current project, or by converting another project into a baseline. Converted projects leave the EPS hierarchy. You can restore a baseline to make it a project again — after edits you can re-baseline it. Copy titles get a - Bx suffix (B1, B2, …), and you can rename them.

Planned Start / Planned Finish are live schedule dates, not that snapshot. The scheduler can update them until the activity starts; then they hold. UI columns like BL Project Start / BL1 Start read dates from the assigned baseline. Those are display fields, not extra TASK columns.

Create, Update, Restore, Assign — four different commands

Planners use one word, "baseline," for several distinct operations. They are not interchangeable:

Create (Add) — save a copy of the current project as a new baseline, or convert another project into a baseline of the current one.
Update — merge selected current-project data into an existing baseline, without restoring it or creating a new one. Oracle warns that creating a brand-new baseline mid-project "may not yield accurate comparison results," which is exactly why Update exists. Project calendars, activity codes, and the WBS are always updated whether you pick them or not; Early/Late Start/Finish are never touched by Update — those are scheduler-calculated and only change if you restore, schedule, and re-baseline.
Restore — turns the selected baseline back into a project you can edit directly, in the same EPS node it was linked to.
Assign — sets which baseline is Project / Primary / Secondary / Tertiary for comparison. It does not write any data into the snapshot itself.

Copy and Delete also exist (duplicate a baseline under the same project, or remove one). None of these six is "the" baseline command — the snapshot is inert data; these are the operations that touch it.

What the XER actually holds

TASK has target_start_date / target_end_date — Oracle labels Planned Start / Planned Finish. There are no BL_* columns on TASK. Do not read planned dates as baseline dates.

sum_base_proj_id is a pointer: which project is the Project Baseline. It is not the snapshot rows. last_baseline_update_date records when a baseline was last touched by Update — Oracle does not say which PROJECT row (current or baseline) carries it, so do not over-claim which side you are reading. Oracle disagrees with itself on file formats: Professional says XER does not export or import baselines and P6 XML does; EPPM’s XER import wizard can pick baselines. For a typical project XER, do not claim it carries Project Baseline bars the way P6 XML does.

Microsoft Project

A baseline is fields on the task, not a second project. Microsoft: about 20 reference points across five categories (start, finish, duration, work, cost). You can save 11 per project — the unnumbered Baseline plus Baseline1–10. An interim plan is a lighter object: it stores only start and finish (Start1–10 / Finish1–10), up to 10 of them. Do not map an interim plan to a P6 baseline; it is missing duration, work, and cost.

Set Baseline copies the currently scheduled fields into the matching baseline fields — Baseline Start/Finish stay "NA" and Baseline Duration reads "0 days" until you do. Set Baseline can also update an already-saved baseline (entire project or selected tasks, with roll-up options), which is Project's closest analogue to P6's Update command — but Microsoft's own tip suggests saving a second baseline or interim plan instead of overwriting one, and unlike P6, Project never converts another file into a baseline. Variance fields (Start Variance, Finish Variance, etc.) read against the unnumbered Baseline only, not Baseline1–10, unless you build a custom comparison.

Same idea (a frozen plan). Not the same object. P6 Planned Start is not MSP Baseline Start; P6 BL1 Start is a read from an assigned baseline project, while MSP Baseline1 Start is a field sitting on the task itself.

	P6	Project
What is stored	A baseline project (copy)	Baseline fields on the task
How many in play	Project Baseline + three user baselines	Baseline plus Baseline1–10 (11 total)
Not the baseline	Planned Start / `target_*`	Current Start / Finish
Lighter snapshot	n/a	Interim plan — Start/Finish only, up to 10
Typical export	P6 XML can carry bars; a typical XER often does not	MSPDI Baseline nodes on the task

This lesson is one pair of bars: snapshot versus current. It is not a variance product, not SPI, and not Earned Schedule. Planned Value for SPI(t) still comes from this snapshot — not from Planned Start.

What it is not

A baseline is not Planned Start, not the Data Date, and not “the current project used as baseline” pretending to be a second stored copy. UI columns such as BL Project Start are reads from the assigned baseline project. They are not extra TASK columns. Microsoft Project’s Baseline Start is a field on the task — same idea, not the same object.

Must not

Treat target_start_date / target_end_date as baseline dates.
Treat MSP Baseline Start as P6 Planned Start.
Invent a BASELINE XER table.
Treat “current project used as baseline” as a stored second copy.
Claim a typical XER carries snapshot bars the way P6 XML does.
Treat Update as if it were Create, Restore, or Assign — it only merges selected data into an existing baseline.
Treat an MSP interim plan as equivalent to a full baseline.