Flowchart predefined process

A rectangle with doubled side bars.

Also known as: Predefined process box, Double bar rectangle

Engineering & technicalEveryday & digitalStandard profile

Meanings

The flowchart symbol for a step defined in detail elsewhere, drawn as a rectangle with a second line inside each vertical side.

Officially standardisedVerified fact
Marks a step whose detail is defined in a separate flowchart.
Contexts: Technical drawing, Software
Officially standardisedVerified fact
Lets one diagram stay readable by deferring detail, which is the only mechanism the notation has for managing size.
Contexts: Technical drawing, Software

A rectangle with an additional vertical line drawn just inside each of its two vertical sides.

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

ISO 5807, Information processing — Documentation symbols and conventions
International Organization for Standardization · retrieved 2026-08-25
The international standard defining flowchart and program documentation symbols. Cited for a symbol's identity and defined meaning. The standard's own drawings are not reproduced.

Last reviewed 2026-08-25

Meanings

The flowchart symbol for a step defined in detail elsewhere, drawn as a rectangle with a second line inside each vertical side.

Officially standardisedVerified fact

Marks a step whose detail is defined in a separate flowchart.

Officially standardisedVerified fact

Lets one diagram stay readable by deferring detail, which is the only mechanism the notation has for managing size.

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

ISO 5807, Information processing — Documentation symbols and conventions
International Organization for Standardization · retrieved 2026-08-25
The international standard defining flowchart and program documentation symbols. Cited for a symbol's identity and defined meaning. The standard's own drawings are not reproduced.

Last reviewed 2026-08-25