# Entities are declared in '[' ... ']'. All attributes after the entity header
# up until the end of the file (or the next entity declaration) correspond
# to this entity.
[Person]
*name
height
weight
`birth date`
+birth_place_id

[`Birth Place`]
*id
`birth city`
'birth state'
"birth country"

# Each relationship must be between exactly two entities, which need not
# be distinct. Each entity in the relationship has exactly one of four
# possible cardinalities:
#
# Cardinality    Syntax
# 0 or 1         ?
# exactly 1      1
# 0 or more      *
# 1 or more      +
Person *--1 `Birth Place`