of the mask 10 and spans the entire trough 16 formed in the cone side 12 the cone side actual tie bar 26 is said to u201c correspond u201d to the grade side actual tie bar 20 because it is relatively close to having the same location in terms of position on the mask 10 and differs in location only based on cone side 12 or grade side 14 it will be seen however that the cone side actual tie bar 26 may be slightly offset from the grade side actual tie bar 20 vertically horizontally or both and still be considered to be u201c corresponding u201d to the grade side actual tie bar 20 the slight offset is useful to enhance beam clearance in some portions of the mask 10 configuration 4 is similar to configuration 3 in that configuration 4 also has a grade side actual tie bar 20 and a corresponding tie bar on the cone side 12 however configuration 4 has a cone side virtual tie bar 28 that corresponds to the grade side actual tie bar 20 the cone side virtual tie bar 28 is distinguished by a gap 30 that extends from the surface of the cone side 12 to the inner most limit 32 of the grade side actual tie bar 20 configuration 5 is similar to configuration 4 in that configuration 5 has a cone side virtual tie bar 28 however the cone side virtual tie bar 28 of configuration 5 corresponds to a grade side virtual tie bar 22 rather than a grade side actual tie bar 20 the gap 30 of the cone side virtual tie bar 28 is shown as being aligned with the gap 24 of the grade side virtual tie bar.