Milan:

No problem. If the index has an entry in sysmaster:systabnames then it is detached. An attached index will be stored within the parent table's partition and not have an entry there. That's the easiest way. Example, the attached index on the systables table on tabid:

> select * from systabnames where dbsname='art' and tabname = 'tabid';

No rows found.

Versus a detached index:
> select * from systabnames where dbsname='sysmaster'  and tabname = 'flags_text_ix1';

partnum  1049505
dbsname  sysmaster
owner    informix
tabname  flags_text_ix1
collate  en_US.819
dbsnum   1

1 row(s) retrieved.

Within the database's catalog you can figure this out as well. If you query sysfragments for the parent table's tabid and a fragtype = 'I' and indexname = 'name-of-the-index' there will be no rows for an attached index while a detached index will have at least one sysfragments entry. Example, the attached index on the systables table on tabid:

> select * from sysfragments where tabid = 1 and fragtype = 'I' and indexname = 'tabid';

No rows found.

Versus a detached index:
> select *

> from sysfragments

> where tabid = 245 and fragtype = 'I' and indexname = 'flags_text_ix1';

fragtype    I
tabid       245
indexname   flags_text_ix1
colno       0
partn       1049505
strategy    I
location    L
servername
evalpos     0
exprtext
exprbin     <BYTE value>
exprarr     <BYTE value>
flags       0
dbspace     rootdbs
levels      3
npused      42.00000000000
nrows       17.00000000000
clust       27.00000000000
partition   rootdbs
version     1
nupdates    0.00
ndeletes    0.00
ninserts    343.0000000000

1 row(s) retrieved.

To find all attached indexes in a database besides those on the catalog tables, use this query:

select tabname, idxname
from systables st
join sysindexes si
  on st.tabid = si.tabid
left outer join sysfragments sf
  on st.tabid = sf.tabid
   and sf.fragtype = 'I'
 where sf.tabid is null
   and st.tabid > 99;

tabname  no_privs
idxname  no_privs_ak1

1 row(s) retrieved.

So this table:

$ myschema -d art -t no_privs -q
CREATE TABLE "art".no_privs (
       one SERIAL(1) NOT NULL
) IN datadbs_1 EXTENT SIZE 16 NEXT SIZE 16 LOCK MODE PAGE;

{
       Please review extent sizing and adjust to allow for growth.
}

REVOKE ALL ON "art".no_privs FROM public AS "art";
CREATE INDEX "art".no_privs_ak1 ON "art".no_privs (
       one ASC
) USING btree IN TABLE;

To find all attached indexes in a database besides those on the catalog tables, use this query:

select tabname, idxname
from systables st
join sysindexes si
  on st.tabid = si.tabid
left outer join sysfragments sf
  on st.tabid = sf.tabid
   and sf.fragtype = 'I'
 where sf.tabid is null
   and st.tabid > 99;

tabname  no_privs
idxname  no_privs_ak1

1 row(s) retrieved.

So this table:

$ myschema -d art -t no_privs -q
CREATE TABLE "art".no_privs (
       one SERIAL(1) NOT NULL
) IN datadbs_1 EXTENT SIZE 16 NEXT SIZE 16 LOCK MODE PAGE;

{
       Please review extent sizing and adjust to allow for growth.
}

REVOKE ALL ON "art".no_privs FROM public AS "art";
CREATE INDEX "art".no_privs_ak1 ON "art".no_privs (
       one ASC
) USING btree IN TABLE;

To find all attached indexes in a database besides those on the catalog tables, use this query:

select tabname, idxname
from systables st
join sysindexes si
  on st.tabid = si.tabid
left outer join sysfragments sf
  on st.tabid = sf.tabid
   and sf.fragtype = 'I'
 where sf.tabid is null
   and st.tabid > 99;

tabname  no_privs
idxname  no_privs_ak1

1 row(s) retrieved.

So this table:

$ myschema -d art -t no_privs -q
CREATE TABLE "art".no_privs (
       one SERIAL(1) NOT NULL
) IN datadbs_1 EXTENT SIZE 16 NEXT SIZE 16 LOCK MODE PAGE;

{
       Please review extent sizing and adjust to allow for growth.
}

REVOKE ALL ON "art".no_privs FROM public AS "art";
CREATE INDEX "art".no_privs_ak1 ON "art".no_privs (
       one ASC
) USING btree IN TABLE;