[A-Za-z][A-Za-z0-9_']*
all-uppercase = system name
Identifiers must start with a letter A-Z or a-z,
then these letters, the digits 0-9, the underscore _
and the single-quote character ' are allowed.
All-uppercase names are reserved for
system names,
i.e. for functions, constants and variables
that come pre-installed with Eas
(or may be included in Eas at a later time).
All system names are all-uppercase.
Programmers using Eas should only define
all-lowercase and mixed-case identifiers.
Examples for valid identifier names:
myvariable
MyVariable
my_variable
my'variable
A'SYSTEM'NAME
Languages comparison:
JS:
res=Math.sin(Math.pi/4*diam*diam)
Pascal:
Res:=Sin(Pi/4*Diam*diam);
PHP:
$res=sin(PI/4*$diam**2);
Eas:
res SIN:PI/4*diam^2