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Update LEN function behavior details in documentation #378

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4 changes: 4 additions & 0 deletions query-languages/dax/len-function-dax.md
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Expand Up @@ -32,6 +32,10 @@ A whole number indicating the number of characters in the text string.

- If you use LEN with a column that contains non-text values, such as dates or Booleans, the function implicitly casts the value to text, using the current column format.

- Starting with desktop january release, user can set new model property UnicodeCharacterBehavior. Depending on value of the property, the output of LEN(<text>) function changes.
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@jeroenterheerdt jeroenterheerdt Dec 17, 2025

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I'd recommend we don't make it so dependent on the january release in the docs. I'd just say: In recent versions, you can set the UnicodeCharacterBehavior property.

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The month name "january" should be capitalized to "January" for proper noun capitalization. Additionally, "user" should be "users" or "the user" for better grammar.

Suggested change
- Starting with desktop january release, user can set new model property UnicodeCharacterBehavior. Depending on value of the property, the output of LEN(<text>) function changes.
- Starting with the January desktop release, users can set the new model property UnicodeCharacterBehavior. Depending on value of the property, the output of LEN(<text>) function changes.

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- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) will return => 1. This will be new behavior of LEN function.
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@jeroenterheerdt jeroenterheerdt Dec 17, 2025

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isn't there a ' missing? len('🍕')? same a couple of lines earlier.

Comment on lines +36 to +37
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The string literal '😀 is missing a closing single quote. It should be '😀' to properly close the string.

Suggested change
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) will return => 1. This will be new behavior of LEN function.
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀') will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀') will return => 1. This will be new behavior of LEN function.

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Comment on lines +36 to +37
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The function name should be consistently uppercase. Change "len('😀)" to "LEN('😀')" to match the standard DAX function naming convention used throughout the documentation (e.g., line 14, 31, 33, 41).

Suggested change
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) will return => 1. This will be new behavior of LEN function.
- With CodeUnits default value of UnicodeCharacterBehavior property, the LEN('😀') will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the LEN('😀') will return => 1. This will be new behavior of LEN function.

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Comment on lines +36 to +37
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The function name should be consistently uppercase. Change "len('😀)" to "LEN('😀')" to match the standard DAX function naming convention used throughout the documentation (e.g., line 14, 31, 33, 41).

Suggested change
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) will return => 1. This will be new behavior of LEN function.
- With CodeUnits default value of UnicodeCharacterBehavior property, the LEN('😀') will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the LEN('😀') will return => 1. This will be new behavior of LEN function.

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Comment on lines +36 to +37
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Consider replacing the informal "=>" notation with clearer language such as "will return 2" or "returns 2" to be consistent with more formal technical documentation style.

Suggested change
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) will return => 1. This will be new behavior of LEN function.
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) returns 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) returns 1. This will be new behavior of LEN function.

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Comment on lines +35 to +37
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The new documentation about UnicodeCharacterBehavior contradicts the existing remark on line 31 which states "LEN always counts each character as 1, no matter what the default language setting is." Since the behavior now changes based on the UnicodeCharacterBehavior property setting, line 31 should be updated to clarify that this statement applies only to the default CodeUnits behavior, or be revised to reflect the conditional behavior.

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Comment on lines +36 to +37
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The string literal '😀 is missing a closing single quote. It should be '😀' to properly close the string.

Suggested change
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀) will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀) will return => 1. This will be new behavior of LEN function.
- With CodeUnits default value of UnicodeCharacterBehavior property, the len('😀') will return => 2. This is old behavior of LEN function.
- With CodePoints value of UnicodeCharacterBehavior property, the len('😀') will return => 1. This will be new behavior of LEN function.

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## Example

The following formula sums the lengths of addresses in the columns, [AddressLine1] and [AddressLine2].
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