This paper presents the projectile fragments emerged from non-central events of 3.7A GeV 16O collisions with nuclear emulsion. The charges of these fragments were carefully measured. The distributions of those charges were given and fitted by Gaussian shapes. The topology of 16O fragmentation is given. Projectile fragmentation from collisions of 16O with emulsion nuclei at 3.7 A GeV are investigated in terms of production of alpha-clusters. The produced alpha cluster is found to be the most probable fragment than all other possible charge of projectile fragmentations. The mechanism of projectile fragments for production of α-cluster is found to be independent on collision energy in the energy range 2 to 200 A GeV. Inelastic cross-section for interactions with alpha fragments is weakly dependence on projectile mass number and this dependence disappear for high values of multiplicity. The probability distribution of α-clusters decreasesby certain valuewith high multiplicity. Production of α-clusters takes form of quantization thatdifferentfrom tools of all other possible charges of projectile fragmentations. This discreet production of α-clusters is independent on target size but there is certain negative effect of target mass of the multiplicity of α-clusters. Thefrequency distribution of charges of 16O projectile fragments is gradually decrease from maximum at α-clusters and followed to carbon, beryllium, and boron it explained by consider the given nuclei as a collection of α-clusters. The minimum frequency is for lithium and nitrogen. The mechanism of projectile fragmentation to produce all channels of possible charges is independent on the energy of collisions but also on the nature of the parent projectile nucleus.