Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: DVDrw 20X Lightscribe Black Face Plate/Metal Enclosure
Product description: 20X EXT DVDRW DR DUAL FMT DL LIGHT SCRIBE
Product feature: I/O Magic, 20x DVD RW Drive, Dual Format/Double Layer, DVD RW Drive
Product brand: I/OMagic
Target attributes: Type
Answer: attribute: type
value: ext
source: product description