<mat-form-field [formGroup]='formGroup'
    matTooltip='Predefined collections of layers, for different kinds of work or domains of applications'
    matTooltipPosition="right"
    >
    <mat-label>Base map</mat-label>
    <mat-select multiple formControlName='baseMaps'>
        <mat-option *ngFor="let bm of mapDataService.mapInitData.baseMaps"
            (onSelectionChange)="selChange($event, bm)"
            [value]="bm.name"
            [title]="bm.stores.join(', ')"
            >
            {{ bm.name }}
        </mat-option>
    </mat-select>
</mat-form-field>