to either side also it is noted that the relative lack of accuracy and precision in reading a bubble level on a job site contributes to the deviations from u201c true vertical u201d u201c true vertical u201d is taken to mean a geometrically accurate vertical positioning also as used herein a u201c right angle u201d such as is formed by the parallelogram of the aperture guide when a level is used to align a block guide to a vertical position is meant to be formed when a u201c vertical u201d positioning or alignment is made within any of the ranges of tolerances defined in the above paragraph also as used herein a block guide is taken to mean a device capable of assisting in the alignment of bricks blocks stone and other components of a wall structure assembled by mortar as used herein the term u201c block u201d is meant to encompass bricks cement blocks other types of blocks stone and other components capable of assembly by mortar into a wall this type of construction is referred to as u201c masonry construction u201d all patents patent applications publications texts and references discussed or cited herein are understood to be incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually set forth in its entirety in addition all references patents applications and other documents cited in an invention disclosure statement examiner 39 s summary of cited references or otherwise.