Basic non-halal (or "haram" i.e., forbidden) food group are consisting of:
- Pork - both farm raised pork, and wild ones or hogs
- Blood - running blood, while traces on meat are acceptable
- Carrion - including carcass of animal dead not by proper butchering
- Sacrificial animals - animals used for ritual killings, or slaughtered not in the name of God
- Top land predators - animals which hunts by its claws, fangs, or combination of both
- Khamr - alcoholic beverages, i.e. either fermented or distilled drinks which causes drunk
Excluded from the list are carcass from dead sea animals, i.e. fishes, whales, which is allowed to be consumed -- given that its condition is still good for consumption.
Halal status in Indonesia
As the case with Indonesia, despite of having 85% of its 240 million population moslem, Indonesia are still considered lacked behind in Halal standardization, this is due mostly because people are still having comfort relying on ethnic stereotyping; if you looks like pribumi (natives), you're most likely to produce (and eat) halal food.
However this is a false assumption since there are many food related practices, even traditional ones from a moslem dominant population, that actually contradict with Islamic rules of diet. Especially since Islam teaching in many parts of Indonesia are still mixed with traditions, and other belief system from the pre-Islamic era, e.g. animism and dynamism. For example, the consumption of marus or dadih, which is a coagulated blood that's seasoned and cooked into a firm consistency; it is forbidden in Islam but traditionally it's a delicacies.
Also taking into concern the foul practices merchant does in the name of profit, or other misbehaves caused by simply naive unawareness.
Without too much dissecting or validating its appropriateness, following are the types of Halal status that commonly applies in Indonesia, and works on general situation elsewhere as well:
HL1 - Halal by personal observation and assumption
Food in this category are considered Halal by observer's assumption, with observation mostly based on main ingredients used; that it is not from the forbidden group of food.
It usually applies when a more thorough inspection of the food process is not possible, while the observable parts of the food/drink are considered as halal.
There's an example of this act practiced back in prophet Muhammad saw. time: once there was a gift of meat from non-muslim people but those receiving them are unsure whether Allah name was mentioned upon the butchering or not. So they asked Rasulullah about it, and Rasulullah said
"Mention Allah name upon it and eat it" (Shahih Bukhari) .However due to different understanding and level of halal knowledge Moslem have, expect a diverse opinion on the conclusion, even though there are examples of this kind of practice were done in the prophet's presence.
Some would even prefer to ditch all food fell into this category in thinking that it's better to leave a doubt and choose what's firm.
HL2 - Halal by seller's claim
Food in this category are claimed Halal by the seller's claim, and most halal food in Indonesia are fall into this category. This kind of claim is usually good, and should violation of halal dietary rules ever happens, i.e., usage of seasoning thought to be halal while they are not, they most likely are not intended.
HL3 - Halal by certification from legitimate bodies
Food in this category are proclaimed Halal by one or more legitimate bodies that eligible to do formal certification. Most halal food products sold for mass consumption in Indonesia fall into this category, and is considered as the strongest level of Halal status by most people.
In Indonesia, though the general food inspection and standardization are done by the Health Department, specific for Halal certification it is done by LPPOM MUI, a branch of the MUI (Majelis Ulama Indonesia) -- Indonesian Council of Muslim Clerics.
Some moslem though, who applies a very strict halal diet, or does not acknowledge the legitimate bodies, would still prefer to use the combination of HL1 & HL2, that is only buying similar products from a vendor they validate themselves, where they're able to inspect the whole process themselves, and mostly known the vendor personally, or recommended by other brothers of the same strictness.
Beside of the main three, there is also one type of Halal-related status that grows more popular these days in Indonesia, especially in the big cities:
HL0 - Halal by no-pork claim
Since pork is the "superstar" of non-halal foods, and it's the main judgement criteria used in Indonesia, a lot of new restaurants who don't certificate themselves as halal, but tries to appeal to as wide customers as possible, i.e.: Moslem, excluding pork from their menu and uses the claim of "no pork".
This usually applies with restaurants specializing in modern and foreign food opening in big cities where as though Moslem is still the majority population, they are less stricter or are not really religious. For example: low cost Steak houses, Hip Sushi restaurants, modern Chinese restaurants, budget Italian restaurants.
While claiming they serves no pork, those who serves imported meats usually provide no clarity on its halal status either; they don't guarantee the absence of other non-halal substances as well, which usually presented in the form of liquor-based seasoning such as wines, wine-based vinegars, sake, mirin, etc. Hence halal status in this "no-pork" claim usually is only loosely perceived, while the fact is questionable.
Halal Food in Bali
Outside of the popularity of Babi Guling (Suckling Pig), Balinese cuisines are also rich with dishes containing chicken and salt water fishes. There are also conventional meat producers that guarantees halal status of their food, and their main market is the halal food vendors around Bali. However most chicken used in Balinese traditional dishes are brought from traditional market which are not specifically prepared to Islamic standards - but does not known to contradict either. Hence of halal status, HL1 are most common.
As with other kind of traditional dishes beside Balinese, you need to pay special attention since Halal is a lesser standard applied in Bali, so the non-halal non-Balinese dishes are also abundantly sold here, including the Cwi Mie Malang with pork oil (haram substance) we encountered in one East Javanese restaurant near Renon area.
Those that applies HL2 standards usually includes Islamic connection in their business name, i.e. "Warung Muslim Banyuwangi", and so far this is your best chance of encountering halal food in Bali. Other choice in this HL2 category is the ethnic-stereotype based that is always guaranteed halal 100%: the Padangnese restaurants.
They never put "halal" in their restaurant names or stated claims as it would be considered laughable for stating something so obvious -- though not 100% people from Padang region (Western Sumatera) are muslim.
On a lighter note, it's a common thing in Indonesia to label halal food with "100% Halal" claim, however such claims are more of an exaggeration than fact, since: even a 0.1% inclusion of a known non-halal substance would waive the halal status, i.e. no such thing as "99% halal" label; and in practice no one can truly examines every parts or process that goes or included in the food preparation to warrant the claim.
Halal compatible standards
The Holly Quran also mentions that food prepared by "Ahli Kitab," or people from other Samawi religions preceding Islam (Christians, and Jews), are good as well:
"This day [all] good foods have been made lawful, and the food of those who were given the Scripture is lawful for you and your food is lawful for them (...)" [QS Al-Maidah: 5](byms)
 Source: "Halal dan Haram dalam Islam," DR. Yusuf Al-Qardhawi, PT. Bina Ilmu, 1993: http://media.isnet.org/islam/Qardhawi/Halal/201172.html