public function invocation( $isbn, $isbn_text_font, $isbn_text_size, $text_font, $text_size ) {

		$ps[] = "50 50 moveto ({$isbn}) (includetext isbntextfont={$isbn_text_font} isbntextsize={$isbn_text_size} textfont={$text_font} textsize={$text_size})";
		$ps[] = '/isbn /uk.co.terryburton.bwipp findresource exec';

		return implode( "\n", $ps ) . "\n";
	}
public function invocation( $isbn, $isbn_text_font, $isbn_text_size, $text_font, $text_size ) {

		$ps[] = "50 50 moveto ({$isbn}) (includetext isbntextfont={$isbn_text_font} isbntextsize={$isbn_text_size} textfont={$text_font} textsize={$text_size})";
		$ps[] = '/isbn /uk.co.terryburton.bwipp findresource exec';

		return implode( "\n", $ps ) . "\n";
	}
public function invocation ( $ isbn , $ isbn_text_font , $ isbn_text_size , $ text_font , $ text_size ) { $ ps [ ] = "50 50 moveto ({$isbn}) (includetext isbntextfont={$isbn_text_font} isbntextsize={$isbn_text_size} textfont={$text_font} textsize={$text_size})" ; $ ps [ ] = '/isbn /uk.co.terryburton.bwipp findresource exec' ; return implode ( "\n" , $ ps ) . "\n" ; }
ISBN Invocation Code.

@see https://github.com/bwipp/postscriptbarcode/wiki/ISBN
@see https://github.com/bwipp/postscriptbarcode/wiki/Symbol-Dimensions
@see https://github.com/bwipp/postscriptbarcode/wiki/Text-Properties

@param string $isbn
@param string $isbn_text_font
@param float $isbn_text_size
@param string $text_font
@param float $text_size

@return string
ISBN Invocation Code .