Arguments

featureId  (integer)  'handle' identifier of the 'GIS Feature' to query
attDef  (AttributeDefinition list)  attribute definition list, to be used for the attribute update

AttributeDefinition is a list defined as :
(list AttributeName AttributeType AttributeValue)

with
  AttributeName  (string)  the name of the Attribute
  AttributeType  (integer)  the type of the Attribute (see the Type Constants enumeration "Civil GIS Attribute Type")
  AttributeValue  (string or integer or double)  the value to be assigned : string or integer or double

Return

T on success, or NIL

Example

(vl-load-gis)  T
(setq layers (gis:get-layers))  ("shp_3857_point_2d_utf8")
(setq name (car layers))  "shp_3857_point_2d_utf8"
(setq layerId (gis:get-layer name))  1736983018068
(setq features (gis:layer-get-features layerId))  (1685094904232 1685094904233)
(setq featureId (car features))  1685094904232
(setq newAttribute (gis:layer-add-attribute layerId (list "NewInt64" 1 456)))  T
(gis:feature-has-attribute featureId "NewInt64")  T

Remarks

also see function (gis:feature-get-attribute);

a 'GIS Feature Attribute' represents a "Column" in the GIS Database table; each 'GIS Feature' (built-up from dwg entities) is a row in such table;
the 'GIS Feature Attribute' name string is always handled as case-insensitive !