The psyche in humanitarian socionics is considered as a three-dimensional system of layers stratified on each other: the deep core - the middle layers - the surface. The quality and stability of these layers naturally change from the deep core to the outer shell. The closer to the outer border, the more flexible the psyche is and the less energy is required to apply it in order to transform it.
The type itself is in the deep core. His device during the life of the means of the psyche itself does not change (maximum rigidity and stability). The term of its existence is equal to the time of existence of the mental system itself. Thus, the socionic type is an invariant of the psyche. In order to directly detect and "open" it, you need to attach a maximum load to the psyche.
Further, over the core lies the middle layer, which possesses not absolute, but only relative stability. It is called a type option, or a subtype. Relative stability means that the subtype can change, although this happens rarely and only under the influence of severe life shocks in those moments when the psyche is in a transitional state (for example, adolescence, midlife crisis, etc.). In the case of the individual psyche, we are talking about a period of tens of years. Type option is manifested primarily as a person's tendency to perform a certain role in the primary group.
And, finally, the most “soft” and mobile mental layer is formed outside - a functional profile, which is often the imprint of the current habitat of the wearer of the type. It exists for as long as the type carrier resides in it. The normal life of a profile is about several years. In this case, also talk about the stereotypes of behavior. For example, the military environment makes a person rougher, female education contributes to the formation of a profile with emotionality, etc.