The Label Fields list at the top of the ArcMap Label Expression dialog box doesn’t show the complete name of long field names from the layer.
Field names are shown in columns. If the field names are too long for the columns, the complete name of the field is not displayed. Consequently, it can be difficult to distinguish between different fields.
The dialog box does not support field aliases. Also, the columns are not resizable.
Remember the Label Fields lists the fields in the same order as they are listed in the layer's table.
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