Standard or regulation

Unicode Standard Annex #9: Unicode Bidirectional Algorithm

Unicode Consortium, Unicode Consortium, 2026

Read the original

Read on October 16, 2026

What it is: The Unicode standard that specifies how text mixing right-to-left scripts such as Arabic and Hebrew with left-to-right text, digits and Latin words is ordered on screen.
How much weight it carries: The authoritative standard that text editors and browsers implement. The page we read is marked as a draft revision, but the passages quoted are long-standing.

Facts taken from this source

The Unicode standard says that when right-to-left scripts use digits written from left to right, the text is actually bidirectional, a mixture of right-to-left and left-to-right text.
“Whenever right-to-left scripts, for example, use digits that are written from left to right, the text is actually bidirectional” (Section 1 Introduction)
The Unicode Standard prescribes a memory representation order known as logical order, which is the order characters are stored in, separate from the order they are displayed in.
“The Unicode Standard prescribes a memory representation order known as logical order” (Section 1, Introduction)
Unicode's bidirectional algorithm changes a European number to an Arabic number when the nearest strong character before it is an Arabic letter.
“If an AL is found, change the type of the European number to Arabic number.” (Rule W2 (weak types))
Unicode's bidirectional algorithm says that neutral characters, such as punctuation and spaces, generally take the direction of the surrounding text, and take the embedding direction when the two sides conflict.
“Generally, NIs take on the direction of the surrounding text. In case of a conflict, they take on the embedding direction.” (Rule N1 and N2 (neutral types))
The Unicode bidirectional algorithm calls the left-to-right and right-to-left bidirectional types strong types, and characters of those types strong directional characters.
“The bidirectional types left-to-right and right-to-left are called strong types” (Section 3.2 Bidirectional Character Types)

Pages that rest on this source

Standard or regulation

Unicode Standard Annex #9: Unicode Bidirectional Algorithm

Unicode Consortium, Unicode Consortium, 2026

Read the original

Read on October 16, 2026

What it is: The Unicode standard that specifies how text mixing right-to-left scripts such as Arabic and Hebrew with left-to-right text, digits and Latin words is ordered on screen.
How much weight it carries: The authoritative standard that text editors and browsers implement. The page we read is marked as a draft revision, but the passages quoted are long-standing.

Facts taken from this source

The Unicode standard says that when right-to-left scripts use digits written from left to right, the text is actually bidirectional, a mixture of right-to-left and left-to-right text.
“Whenever right-to-left scripts, for example, use digits that are written from left to right, the text is actually bidirectional” (Section 1 Introduction)
The Unicode Standard prescribes a memory representation order known as logical order, which is the order characters are stored in, separate from the order they are displayed in.
“The Unicode Standard prescribes a memory representation order known as logical order” (Section 1, Introduction)
Unicode's bidirectional algorithm changes a European number to an Arabic number when the nearest strong character before it is an Arabic letter.
“If an AL is found, change the type of the European number to Arabic number.” (Rule W2 (weak types))
Unicode's bidirectional algorithm says that neutral characters, such as punctuation and spaces, generally take the direction of the surrounding text, and take the embedding direction when the two sides conflict.
“Generally, NIs take on the direction of the surrounding text. In case of a conflict, they take on the embedding direction.” (Rule N1 and N2 (neutral types))
The Unicode bidirectional algorithm calls the left-to-right and right-to-left bidirectional types strong types, and characters of those types strong directional characters.
“The bidirectional types left-to-right and right-to-left are called strong types” (Section 3.2 Bidirectional Character Types)