This looks like the International Classification of Diseases (ICD-10) in which Chapter V is Mental and Behavioural Disorders.
https://apps.who.int/classifications/apps/icd/icd10online2007/index.htm?gf00.htm+
This is about
Diagnosis (ie identification of the disease). It doesn't say anything much about what one might expect in terms of Prognosis (ie characteristics and development of the disease).
Within that chapter are codes for Dementia as follows:
(F00) Dementia in Alzheimer's disease
(F01) Vascular dementia
(F02) Dementia in other diseases classified elsewhere
(F03) Unspecified dementia
Each of the above is then further broken down to give more detailed variants. For example, Alzheimer's Disease is classified thus:
F00* Dementia in Alzheimer's disease ( G30.-+ )
Alzheimer's disease is a primary degenerative cerebral disease of unknown etiology with characteristic neuropathological and neurochemical features. The disorder is usually insidious in onset and develops slowly but steadily over a period of several years.
F00.0* Dementia in Alzheimer's disease with early onset ( G30.0+ )
Dementia in Alzheimer's disease with onset before the age of 65, with a relatively rapid deteriorating course and with marked multiple disorders of the higher cortical functions.
Alzheimer's disease, type 2
Presenile dementia, Alzheimer's type
Primary degenerative dementia of the Alzheimer's type, presenile onset
F00.1* Dementia in Alzheimer's disease with late onset ( G30.1+ )
Dementia in Alzheimer's disease with onset after the age of 65, usually in the late 70s or thereafter, with a slow progression, and with memory impairment as the principal feature.
Alzheimer's disease, type 1
Primary degenerative dementia of the Alzheimer's type, senile onset
Senile dementia, Alzheimer's type
F00.2* Dementia in Alzheimer's disease, atypical or mixed type ( G30.8+ )
Atypical dementia, Alzheimer's type
F00.9* Dementia in Alzheimer's disease, unspecified ( G30.9+ )
I suspect that the f 100 in the original post is a typographical error.