WordPress at a glance
function is not described

wp_import_upload_form() WP 2.0.0

Outputs the form used by the importers to accept the data to be imported

Hooks in function
Return

Nothing (null).

Usage

wp_import_upload_form( $action );
$action(string) (required)
The action attribute for the form.

Code of wp import upload form: wp-admin/includes/template.php VER 5.0.3

<?php
function wp_import_upload_form( $action ) {

	/**
	 * Filters the maximum allowed upload size for import files.
	 *
	 * @since 2.3.0
	 *
	 * @see wp_max_upload_size()
	 *
	 * @param int $max_upload_size Allowed upload size. Default 1 MB.
	 */
	$bytes = apply_filters( 'import_upload_size_limit', wp_max_upload_size() );
	$size = size_format( $bytes );
	$upload_dir = wp_upload_dir();
	if ( ! empty( $upload_dir['error'] ) ) :
		?><div class="error"><p><?php _e('Before you can upload your import file, you will need to fix the following error:'); ?></p>
		<p><strong><?php echo $upload_dir['error']; ?></strong></p></div><?php
	else :
?>
<form enctype="multipart/form-data" id="import-upload-form" method="post" class="wp-upload-form" action="<?php echo esc_url( wp_nonce_url( $action, 'import-upload' ) ); ?>">
<p>
<label for="upload"><?php _e( 'Choose a file from your computer:' ); ?></label> (<?php printf( __('Maximum size: %s' ), $size ); ?>)
<input type="file" id="upload" name="import" size="25" />
<input type="hidden" name="action" value="save" />
<input type="hidden" name="max_file_size" value="<?php echo $bytes; ?>" />
</p>
<?php submit_button( __('Upload file and import'), 'primary' ); ?>
</form>
<?php
	endif;
}