Various techniques are known for embossing the design elements of the edge of a coin. One of these techniques is to coin the edge during the hemming process using a machine (straight edger) that simultaneously defines the effective diameter of the planchet. Another technique used to bring the design to the edge of the coin is to perform this operation at the same time as the minting phase.
In particular, the inscriptions and decorations are present in negative on the collar which, due to the compression of the planchet against its walls, transfers the design elements to the edge of the coin.
In some cases, the design elements are not coined correctly due to the incomplete integrity of the engraving due to deformation, wear or breakage of the characters (from E.B.45 to E.B.52).
Furthermore, there could be errors in the composition of the legend by the operator (E.B.53 and E.B.54) or slippage of the machinery.
In extremely rare cases, this error can involve the assembly of the broken shell (particular type of collar usually composed of 3 segments), used at the same time as the typing operation for all those coins that must be minted on the edge with the design elements in relief rather than incuse. In this circumstance, it may happen that (voluntarily or due to the negligence of the press operator) the broken collar is assembled with inverted segments.
This is the case of the famous 500 Lire Guglielmo Marconi which on the edge have the embossed legend REPUBALIANA BLICA IT instead of the REPVBBLICA ITALIANA and of the 500 Lire Caravelle 1958 which present the ITALIANA REPUBBLICA rather than REPVBBLICA ITALIANA legend.