Mystery vintage Ibanez?

[Led Hedstrom]

Hello . First time posting anywhere about this guitar ,I’m hoping someone can solve this Mystery. I currently own-a 1977 Ibanez model number 645 serial number 770323. I have found many pictures and catalogs and believe it to be an original. Where it gets weird is in the sound hole on the Ibanez sticker the model number is actually 645 A . There is also a capital A stamped into back of headstock . I can’t seem to find out anything on this . This model is basically a close copy of a Matin D-18 . I have owned this for about 12 years . It plays and sounds great . Any feed back would be helpful.