bp_get_field_css_class( string|bool $class = false )

	function bp_get_field_css_class( $class = false ) {
		global $profile_template;

		$css_classes = array();

		if ( ! empty( $class ) ) {
			if ( ! is_array( $class ) ) {
				$class = preg_split( '#\s+#', $class );
			}
			$css_classes = array_map( 'sanitize_html_class', $class );
		}

		// Set a class with the field ID.
		$css_classes[] = 'field_' . $profile_template->field->id;

		// Set a class with the field name (sanitized).
		$css_classes[] = 'field_' . sanitize_title( $profile_template->field->name );

		// Set a class indicating whether the field is required or optional.
		if ( ! empty( $profile_template->field->is_required ) ) {
			$css_classes[] = 'required-field';
		} else {
			$css_classes[] = 'optional-field';
		}

		// Add the field visibility level.
		$css_classes[] = 'visibility-' . esc_attr( bp_get_the_profile_field_visibility_level() );

		if ( $profile_template->current_field % 2 == 1 ) {
			$css_classes[] = 'alt';
		}

		$css_classes[] = 'field_type_' . sanitize_title( $profile_template->field->type );

		/**
		 * Filters the field classes to be applied to a field.
		 *
		 * @since BuddyPress 1.1.0
		 *
		 * @param array $css_classes Array of classes to be applied to field. Passed by reference.
		 */
		$css_classes = apply_filters_ref_array( 'bp_field_css_classes', array( &$css_classes ) );

		/**
		 * Filters the class HTML attribute to be used on a field.
		 *
		 * @since BuddyPress 1.1.0
		 *
		 * @param string $value class HTML attribute with imploded classes.
		 */
		return apply_filters( 'bp_get_field_css_class', ' class="' . implode( ' ', $css_classes ) . '"' );
	}