GiD_UnAssignData material|condition <name> <over> <entities> ?wherefield <fieldname> <fieldvalue>?
To unassign materials or conditions of some entities:

<name> is the name of the material or condition; Can use "*" to match all materials
<over> must be: points, lines, surfaces, volumes, layers, nodes, elements, body_elements, or face_elements (elements is equivalent to body_elements);

It is possible to use all_geometry|all_mesh||all to unassign of all entities of geometry or mesh or both. Then <entities selection> must not be provided.

<entities> a list of entities (it is valid to use ranges as a:b ,can use "all" to select everything, "end" to specify the last entity, layer:<layername> to select the entities in this layer) ; if <over> is face_elements then you must specify a list of "entitynumface" instead just "entity".
wherefield <fieldname> <fieldvalue> To unassign this condition only for the entities where the field named 'fieldname' has the value 'fieldvalue'

Example:

GiD_UnAssignData material * surfaces {end-5:end}
GiD_UnAssignData condition Point-Load nodes layer:Layer0
GiD_UnAssignData condition Face-Load face_elements {15 1 18 1 20 2}

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