In order to avoid the risk of loss or theft of the original copy of your Passport, ITAP or ITAS card, or other important documents, and the resulting hassles to replace them, many expatriates keep the original at their home/office in a secure place and carry only a photocopy of the most important identity documents.

Be aware that you may be asked to produce documents by police/other oficials. This is the law that governs this is Article 71 of the Immigration Law:

Setiap Orang Asing yang berada di Wilayah Indonesia wajib: a. memberikan segala keterangan yang diperlukan mengenai identitas diri dan/atau keluarganya serta melaporkan setiap perubahan status sipil, kewarganegaraan, pekerjaan, Penjamin, atau perubahan alamatnya kepada Kantor Imigrasi setempat; atau b. memperlihatkan dan menyerahkan Dokumen Perjalanan atau Izin Tinggal yang dimilikinya apabila diminta oleh Pejabat Imigrasi yang bertugas dalam rangka pengawasan Keimigrasian.

We advise that you keep copies of all your relevant immigration documents at both your office and home, just in case you are caught in an occasional ‘sweeping’ check of expat documents. These are relatively routine operations that are conducted periodically and are not necessarily an effort to harass or otherwise inconvenience the foreign community. They are usually checking for people who are here illegally. If you are here legally and your papers are complete and up-to-date, you have nothing to fear.

Do be careful, however, about bogus officials wanting to check your documents. You should always ask for a ‘surat tugas’ which is the letter from their office detailing what they are allowed to do in the field. If they don’t have a surat tugas … it would be wise to not show them anything! Ask them to return once they have the surat tugas. Or, refer them to the working spouse’s office for any further needed information on documentation.

And by no means pay any bribes to these officials. It would only ensure their repeated return to your place of residence, or encourage them to prey on other unsuspecting foreigners. Again, if you are here legally and have the documents to prove it, there is nothing to fear. If you are approached or threatened by suspicious persons, try to get their names, affiliations and contact numbers.

Mini Glossary

VITAS – Temporary Stay Permit Visa (Visa Izin Tinggal Terbatas)
ITAS = Izin Tinggal Terbatas (Temporary Stay Permit). This is the immigration status/permit by itself. It is materialized by the stamp in your passport that the immigration offices stamps into your passport every year.
KITAS = Kartu Izin Tinggal Terbatas (Temporary Stay Permit Card). This is the yellow card that Immigration will give you after the ITAS has been granted.
ITAP = Izin Tinggal Tetap (Permanent Stay Permit). This is the immigration status/permit by itself. It is evident by the stamp that the immigration office stamps into your passport.
KITAP = Kartu Izin Tinggal Terbatas (Permanent Stay Permit Card). This is the blue card that immigration will give you after the ITAP has been granted.
RPTKA – Expatriate Placement Plan
DPKK – Dana Pengembangan Keahlian dan Keterampilan – Skill & Development Fund Fee
IMTA = Ijin Mempekerjakan Tenaga Kerja Asing = Work Permit for foreigner
Kementerian Tenaga Kerja – Ministry of Manpower
Kantor Imigrasi – Immigration office
DitJen Imigrasi – Directorate General of Immigration
Kementerian Hukum dan Hak Asasi Manusia – Ministry of Justice and Human Rights
WNI – Indonesian Citizen – warga negara Indonesia
WNA – Foreign Citizen – warga negara asing

Source : http://www.expat.or.id/info/docs.html#OriginalDocuments