signalssetupsdesk.online / FIELD NOTES
London wall-clock condition with British Summer Time · Practical reference

AND, OR and unknown: inspect a composite alert with a London time condition

Evaluate an explicitly parenthesised two-condition expression under three-valued logic and a London wall-clock condition, preserving missing or non-contemporaneous evidence.

Publisher: CRYPTO TRADING SIGNALSSource review: 2026-10-20Free to use · No sign-up

AND, OR and unknown: inspect a composite alert with a London time condition

  1. The defaults describe fictional conditions and observations. No price or indicator is loaded and no alert is created.
  2. The expression is exactly (A AND B) AND W or (A OR B) AND W. W is the London wall-clock condition; parentheses are fixed and visible.
  3. Use true, false or unknown. A supplied true/false becomes unusable and therefore unknown if its symbol, saved reference or exact as-of timestamp is missing or mismatched.
  4. Window start is included and end excluded. This worksheet supports same-day HH:MM windows only, not overnight ranges or a market calendar. A blank boundary makes W unknown.
  5. The evaluation instant requires seconds and a known offset. Europe/London conversion includes BST/GMT; a wall-clock range can include both occurrences of an autumn repeated hour.
  6. A true model result is not evidence of a platform trigger, delivered notification or filled order. Export and all calculations are local.

This tool uses the inputs you provide. It does not fetch live market or account data.

Write the parentheses before judging the result

A list of conditions is not yet a complete rule. Both A and B, either A or B, and A or B within a time window can describe different expressions. This worksheet fixes the structure as (A operator B) AND W, prints that structure beside the result and provides all nine combinations of true, false and unknown for A and B.

The aim is to inspect one evaluation, not design an automated trading strategy. Supply the condition wording and its evidence for the same instant. The time condition is computed from that instant and your chosen London wall-clock range. Nothing subscribes to market data or sets an alert; the result is a reproducible explanation of your stated inputs.

Unknown does not mean the condition failed

False means you supplied evidence that the defined condition is not met. Unknown means its truth has not been established in this record. An absent indicator, an unavailable price or a missing reference cannot be converted to false merely to finish the table. The worksheet uses an explicitly declared three-valued model to keep that distinction visible.

In this model, false AND unknown is false because one required condition is already false. True OR unknown is true because one alternative is already true. True AND unknown and false OR unknown remain unknown. This is the worksheet’s logical convention; it is not a claim about how every platform handles missing values, null indicators or scripting-language booleans.

ABA AND BA OR B
trueunknownunknowntrue
falseunknownfalseunknown
unknownunknownunknownunknown
truefalsefalsetrue

A saved true state must still belong to this evaluation

A condition can have been true at one moment without being known at another. Each supplied condition therefore has an exact symbol, timestamp and saved evidence reference. For this narrow audit, the timestamp must identify the same instant as the evaluation. A different offset spelling is acceptable when it represents that same instant.

If a timestamp is earlier, a symbol differs or a reference is blank, the usable state becomes unknown and the reason is displayed. The original supplied state stays in the CSV. A future observation is rejected. The tool does not choose a freshness tolerance or carry a prior state forward; those would be additional assumptions about the condition and data source.

London time changes the third condition, not just the label

The UK government records the 2026 clock changes on 29 March and 25 October. During British Summer Time London is one hour ahead of GMT. This matters when a rule is written in local wall-clock time: a fixed UTC hour does not represent the same London hour throughout the year. The worksheet converts a fully qualified instant using Europe/London before evaluating W.

In the fictional example,07:30 UTC on 20 October is 08:30 in London, which is inside the chosen 08:00–16:30 range. At 07:30 UTC on 26 October, London shows 07:30 and W is false. The range is your research assumption, not exchange opening hours, a recommended trading window or a statement that the offered service operates at those times.

Sources: GOV.UK — When do the clocks change?.

A repeated wall-clock hour needs an explicit interpretation

When the clocks go back, two different instants can display the same London hour with different offsets. A wall-clock range from 01:00 to 02:00 includes both occurrences of 01:30 under this worksheet’s rule. That is intentional: W is a local clock comparison, not a promise that the window lasts exactly one elapsed hour.

The report retains the UTC instant and London offset so the two occurrences are distinguishable. If your intended rule refers to one occurrence only, this simple same-day wall-clock model is insufficient. Do not remove the offset to make the two records look identical. Overnight windows are also outside this tool’s contract; start must be earlier than end on the displayed local day.

An educational expression is not a platform configuration

TradingView’s current multi-condition help page describes its feature as requiring all conditions to be met simultaneously and requiring the same symbol. That supports checking the exact rule before assuming that a list means OR. This page does not mirror that platform’s setup, subscription plans, execution timing or missing-data handling. Its OR option belongs to our explicit local model.

A platform also needs trigger frequency, bar timing, expiration, data availability and notification configuration. A single truth-table result covers none of those operational steps. Passing this worksheet cannot establish that an alert was created, fired or delivered. No account, browser notification permission, webhook or trading connection is requested.

Sources: TradingView — Multi-condition alerts.

Read the worked AND and OR cases side by side

With W=true, A=true and B=unknown, the AND expression remains unknown because the second required condition lacks a known truth value. Change only the operator to OR: one supplied alternative is enough for the base result to be true, and the true time condition keeps the final result true. The nine-row table shows this difference without hiding the unknown input.

Now move the evaluation and both condition timestamps to 07:30 UTC on 26 October while preserving the same 08:00 start. W becomes false, so both final expressions are false under the declared gate. If you instead erase the end time, W becomes unknown. A false base result still determines false; a true base result with an unknown gate does not determine a final true.

Use the table to document a rule, not to claim an outcome

Save the exact expression, condition wording and all supporting references together. The CSV contains both supplied and usable condition states, each discrepancy, the local-time gate and every row of the truth table. That lets another reader see whether a changed answer came from logic, missing evidence or a different evaluation time.

A browser calculation checks the structure of your entry, not the truth of the underlying market condition. Editing invalidates old output; manual copying remains available if clipboard permission fails. The written example and tables remain readable without JavaScript. The separate optional offer link is not needed to use the reasoning or export.

Worked examples

Example 1

At 07:30 UTC on 20 October 2026, London displays 08:30 BST, inside the supplied 08:00–16:30 window, so W=true. A=true and B=unknown give an AND result of unknown. Switching only the operator to OR gives true under this worksheet’s declared logic. Neither result creates or confirms a real alert.

Inspect example inputs
{
  "symbol": "DEMO:PAIR",
  "operator": "AND",
  "as_of": "2026-10-20T07:30:00Z",
  "window_start": "08:00",
  "window_end": "16:30",
  "a_label": "DEMO price condition is met",
  "a_state": "true",
  "a_symbol": "DEMO:PAIR",
  "a_at": "2026-10-20T07:30:00Z",
  "a_reference": "DEMO saved observation A",
  "b_label": "DEMO second condition has no confirmed value",
  "b_state": "unknown",
  "b_symbol": "DEMO:PAIR",
  "b_at": "2026-10-20T07:30:00Z",
  "b_reference": "DEMO record notes missing evidence for condition B"
}

Questions about the method

Does true mean I received a notification?

No. It is a result of the stated local model. Delivery remains unknown.

Why does earlier evidence become unknown?

This audit requires both condition records at the exact evaluation instant. It does not assume persistence or choose a stale-data allowance.

Does the OR option reproduce TradingView multi-condition alerts?

No. The cited feature describes all conditions together; our OR table is a separate educational expression, not an implementation of that feature.

Primary sources and scope

  1. GOV.UK — When do the clocks change?Checked 2026-10-20. 2026 clock-change dates and BST/GMT distinction. No trading hours or alert-service eligibility inferred.
  2. TradingView — Multi-condition alertsChecked 2026-10-20. The documented feature requires all conditions simultaneously and the same symbol. Our three-valued OR model is explicitly separate; no platform configuration performed.

Examples explain a method. They do not predict prices or establish where a trading service is available. Check the named source before relying on future schedules.