receiving slit 82 the slit 82 is generally co linear with the fold line 36 between the pocket forming panel 52 and the rear cover forming panel 32 the slit 82 has tapered ends 83 85 formed by non colinear terminal regions of the slit 82 to facilitate locking the folder 10 and like the tab 68 is generally centered between the upper and lower free edges of the blank 20 fig2 depicts the fold up or forming sequence for forming the blank 20 into the folder 10 first 180 degree folds are made at fold lines 36 and 26 in the direction of arrows a and a 39 respectively whereby the pocket forming panel 52 is brought into overlying relationship with the rear cover forming panel 32 similarly the structural reinforcement panels 62 64 and the clasp 68 are brought into overlying relationship with the front cover forming panel 22 prior to such folding the adhesive areas 56 66 and 66a may be activated or alternatively a contact adhesive may be applied thus the interior pocket forming panel 52 and structural panel 60 are fixed in the positions depicted in fig2 the blank 20 may be supplied to a purchaser such as a film processor or a photographer in the condition just described fig2 also depicts the steps an end user of the folder 10 undertakes having purchased the blank 20 specifically the release layer 50 protecting the adhesive region 49 along the spine 18 is removed by pulling it free in the direction of arrow e the clasp tab 68 is lifted in the direction of arrow c rupturing the nicks 86 holding it in place and reverse folding it 180 degrees outwardly to.