A computer-implemented method of virtually planning a cranial drilled implant guided surgery in a subject said method comprising the planning and generation of production data for a surgical template for guiding the positioning of implants in a subject's cranial bone tissue, said method further comprising generating a first data set based on input data obtained from a reference structure having a defined fixed relation to a bone structure of said subject, said reference structure being an anchoring element inserted into a subject's bone tissue at a site of planned surgical procedure, wherein said anchoring element is one of (i) an anchor screw comprising an apical end, a threaded anchoring section for temporary anchoring in bone tissue, a sleeve section for sliding insertion into a guide sleeve of the surgical template, a stop shoulder matingly cooperating with a top shoulder of the guide sleeve, and a head section for allowing handling of the anchor screw, a (ii) temporary anchoring implant comprising an apical end, a threaded anchoring section for temporary anchoring in bone tissue, a transition section arranged in a fixed relation to a longitudinal axis of the temporary anchoring implant and a head section 60 for allowing handling of the temporary anchoring implant, or (iii) at least the distal part of a temporary two-part anchor screw, said distal part comprising an apical end, a threaded anchoring section for temporary anchoring in bone tissue, a transition section arranged in a fixed relation to a longitudinal axis of the distal part and a connection interface mating with a corresponding interface of a proximal part for providing a releasable connection, virtually planning a position of the guide sleeve of the surgical template based on a position of said anchoring element, wherein said guide sleeve position is planned for locking said surgical template into position during surgery by guiding the insertion of an anchoring screw into a threaded reference bore hole left after removing said temporary anchoring implant or anchor screw from the bone tissue or by guiding the proximal part of the two-part temporary anchor screw to assemble this proximal part with said distal part within the subject's bone tissue, said proximal part comprising a mating interface for connecting with said distal part, a sleeve section 78 for sliding insertion into a guide sleeve of the surgical template, a stop shoulder 71 matingly cooperating with a top shoulder of the guide sleeve, and a head section 70 for allowing handling of the temporary proximal part 7a, generating a second data set comprising topographical data of a cranial anatomical structure or of a soft tissue surface towards which the surgical template is planned to be arranged and/or will abut, said second data set being based on input data obtained from a master structure for said surgical template, said master structure having a defined relation to said reference structure, wherein said master structure is a radiographic guide, a dental impression, or a portion of the subject's actual anatomical situation and associating said first data set with said second data set such that said relation of said reference structure to said master structure is preserved whereby a third data set for production of said surgical template is provided.