Make sure to not use reserved words in future VHDL standards as identifiers. If you do not use any reserved words, your code will be compatible with future VHDL standards without having to make any changes.
1076-2019 - IEEE Standard VHDL Language Reference Manual, 15.10 Reserved words
abs |
fairness |
nand |
select |
access |
file |
new |
sequence |
after |
for |
next |
severity |
alias |
force |
nor |
signal |
all |
function |
not |
shared |
and |
null |
sla |
|
architecture |
generate |
sll |
|
array |
generic |
of |
sra |
assert |
group |
on |
srl |
assume |
guarded |
open |
strong |
attribute |
or |
subtype |
|
if |
others |
||
begin |
impure |
out |
then |
block |
in |
to |
|
body |
inertial |
package |
transport |
buffer |
inout |
parameter |
type |
bus |
is |
port |
|
|
postponed |
unaffected |
|
case |
label |
procedure |
units |
component |
library |
process |
until |
configuration |
linkage |
property |
use |
constant |
literal |
protected |
|
context |
loop |
private |
variable |
cover |
pure |
view |
|
map |
vpkg |
||
default |
mod |
range |
vmode |
disconnect |
record |
vprop |
|
downto |
register |
vunit |
|
reject |
|||
else |
release |
wait |
|
elsif |
rem |
when |
|
end |
report |
while |
|
entity |
restrict |
with |
|
exit |
return |
||
rol |
xnor |
||
ror |
xor |
1076-2008 - IEEE Standard VHDL Language Reference Manual, 15.10 Reserved words
abs |
fairness |
nand |
select |
access |
file |
new |
sequence |
after |
for |
next |
severity |
alias |
force |
nor |
signal |
all |
function |
not |
shared |
and |
null |
sla |
|
architecture |
generate |
sll |
|
array |
generic |
of |
sra |
assert |
group |
on |
srl |
assume |
guarded |
open |
strong |
assume_guarantee |
or |
subtype |
|
attribute |
if |
others |
|
impure |
out |
then |
|
begin |
in |
to |
|
block |
inertial |
package |
transport |
body |
inout |
parameter |
type |
buffer |
is |
port |
|
bus |
postponed |
unaffected |
|
label |
procedure |
units |
|
case |
library |
process |
until |
component |
linkage |
property |
use |
configuration |
literal |
proteccted |
|
constant |
loop |
pure |
variable |
context |
vmode |
||
cover |
map |
range |
vprop |
mod |
record |
vunit |
|
default |
register |
||
disconnect |
reject |
wait |
|
downto |
release |
when |
|
rem |
while |
||
else |
report |
with |
|
elsif |
restrict |
||
end |
restrict_guarantee |
xnor |
|
entity |
return |
xor |
|
exit |
rol |
||
ror |
1076-2002 - IEEE Standard VHDL Language Reference Manual, 13.9 Reserved words
abs |
file |
nand |
select |
access |
for |
new |
severity |
after |
function |
next |
signal |
alias |
nor |
shared |
|
all |
generate |
not |
sla |
and |
generic |
null |
sll |
architecture |
group |
sra |
|
array |
guarded |
of |
srl |
assert |
on |
subtype |
|
attribute |
if |
open |
|
impure |
or |
then |
|
begin |
in |
others |
to |
block |
inertial |
out |
transport |
body |
inout |
type |
|
buffer |
is |
package |
|
bus |
port |
unaffected |
|
label |
postponed |
units |
|
case |
library |
procedural |
until |
component |
linkage |
procedure |
use |
configuration |
literal |
process |
|
constant |
loop |
protected |
variable |
pure |
|||
disconnect |
map |
wait |
|
downto |
mod |
range |
when |
record |
while |
||
else |
reference |
with |
|
elsif |
register |
||
end |
reject |
xnor |
|
entity |
rem |
xor |
|
exit |
report |
||
return |
|||
rol |
|||
ror |
1076-1993 - IEEE Standard VHDL Language Reference Manual, 13.9 Reserved words
abs |
file |
nand |
select |
access |
for |
new |
severity |
after |
function |
next |
signal |
alias |
nor |
shared |
|
all |
generate |
not |
sla |
and |
generic |
null |
sll |
architecture |
group |
sra |
|
array |
guarded |
of |
srl |
assert |
on |
subtype |
|
attribute |
if |
open |
|
impure |
or |
then |
|
begin |
in |
others |
to |
block |
inertial |
out |
transport |
body |
inout |
type |
|
buffer |
is |
package |
|
bus |
port |
unaffected |
|
label |
postponed |
units |
|
case |
library |
procedure |
until |
component |
linkage |
process |
use |
configuration |
literal |
pure |
|
constant |
loop |
variable |
|
range |
|||
disconnect |
map |
record |
wait |
downto |
mod |
register |
when |
reject |
while |
||
else |
rem |
with |
|
elsif |
report |
||
end |
return |
xnor |
|
entity |
rol |
xor |
|
exit |
ror |
entity view is -- Noncompliant: 'view' is a reserved word in VHDL 2019 ... end;
entity fly is ... end;