Separating lines: the dip that gets erased
Start with the one the engine does know, because it is the simpler idea.
Prices have been rising. Monday falls — opens ₹31.00, closes ₹30.50. Then Tuesday opens at ₹31.00 again, the same price Monday opened at, and runs to ₹31.90.
That is bullish separating lines. The name points at the opens: two sessions starting from the same price and going opposite ways. Monday's dip is not reversed so much as skipped — Tuesday begins as though it never happened.
The bearish mirror is the same in a falling market: a rising session, then a long falling one that opens at the same price the rise opened at, erasing the bounce.
Two sessions from the same starting price
Read the two opening prices first. They are the pattern; the closes are the consequence.
Granthara's rules engine returns bullish separating lines. It allows the two opens to differ by up to 5% of the larger range before it stops calling them the same price — a convention, and worth knowing it is one.
Why the open carries this one
Almost every pattern so far has been read from closes and bodies. This one is read from opens, and that is unusual enough to be worth a sentence.
An opening price in a continuous market is where the overnight repricing settled — where the pre-open auction of 01.04.02 came to rest. Two consecutive sessions opening at the same number means the overnight process arrived at the same place twice, despite what happened in between.
Which is why the pattern is filed as continuation rather than reversal. Monday's fall was a session; it was not a repricing. Tuesday's auction did not inherit it.
Tasuki gap: a gap that gets tested and holds
Now the second pattern. Monday rises, ₹30.00 to ₹30.50. Tuesday opens at ₹30.80 — clear above Monday's high of ₹30.60 — and closes at ₹31.10. There is a stretch of price between ₹30.60 and ₹30.75 where nothing traded at all.
Wednesday falls. It opens inside Tuesday's body at ₹31.00 and slides to ₹30.65. And there it stops, one paisa into the gap, and closes.
That is an upside Tasuki gap: a gapped continuation, then a session that falls back and tests the gap without closing it. The whole content of the pattern is the word without. Had Wednesday closed at ₹30.40, below Monday's close, the gap would be filled and the reading would be completely different — the overnight repricing undone within two sessions.
The gap, and the session that tested it
The number to watch is Wednesday's close against Monday's close of ₹30.50, and against Tuesday's open of ₹30.80.
Granthara's rules engine returns no pattern for these three boards — and returns no pattern for the same three with Wednesday closing at ₹30.40 and the gap filled. It cannot tell them apart, because it has no Tasuki rule.
A tool that has never been taught a pattern reports its absence exactly the way it reports a pattern that is not there.
The name your screener does not have
This is the lesson worth carrying out of chapter 04.04, and it is nothing to do with Tasuki.
Granthara's rules engine knows roughly sixty shapes. TA-Lib knows about sixty, not the same sixty. A charting platform's built-in scanner knows another list, usually shorter and usually undocumented. None of them knows every name in the literature, and none of them says so while it is running.
So there are two different reasons a screener stays quiet: the pattern is not on the chart, or the pattern is not in the list. From the outside these look identical, and the second is far commoner than most people assume.
The defence is cheap. Learn the geometry, not the button. You can check this one by eye in four seconds — did the third session close back through the gap, yes or no — and that check is reliable whatever any tool does or does not report.
What these boards permit
Separating lines permit you to say two consecutive sessions opened at the same price and went opposite ways. The Tasuki boards permit you to say a gap was tested and left open at the close.
Neither permits a claim about the session after. The literature files both as continuation patterns, and the word describes the boards already drawn.
And the Tasuki reading has one extra condition worth stating: it depends entirely on a gap, which on Indian equities is an overnight event. Intraday charts of a liquid stock produce very few real gaps, so this is a daily-chart pattern in practice whatever the textbook says.