The EU Visa Code distinguishes between the following visas:

• A visa: for airport transit 
  
  
• C visa: for short stays in the territory of the Schengen states of no more than 90 days over a six-month period from the date of first entry as well as for transit. This is a uniform visa, which allows short-term stays in the entire Schengen area. It is also issued for short-term employment. 
  
  
• D visa: for a longer stay (exceeding 90 days) in the territory of a member country. According to the Schengen Convention, the D visa also permits short stays in the other countries of the Schengen area. The D visa is usually issued for three months but may also be issued for up to twelve months and must specify whether its holder is permitted to work in the respective country. The granting of a national visa is generally subject to the approval of the immigration authorities. Based on the D visa, a long-term residence title may be issued after the entry. 

The German diplomatic representations abroad issue A and C category visas on their own authority. Personal presence of the applicant is usually required for application.

Visas for long-term stays (more than 90 days) in the federal territory can generally only be issued subject to the approval of the relevant immigration authorities, if the applicant has been to Germany once or several times before.  

If the approval of the Federal Employment Agency is required to obtain a visa for intended employment, the appropriate Zentrale für Auslands- und Fachvermittlung (ZAV; English: English: International Placement Services) will be contacted by the German diplomatic representation that processes the application. 

If approval is required, the visa may be issued only after said approval is granted (see also Issuance of a residence title for specific professional groups pursuant to § 7 BeschV).

The French choreographer, the Irish musician, and the German ensemble members from the example, therefore, do not need any residence or work permits for the production in Germany and the European tour. 

The Indian dancer, however, will need a national visa (category D) that is valid for Germany as well as for short stays in other Schengen countries.  

During the visa process, it will be determined whether the proposed activity can be regarded as employment based on the for aliens’ law. In this case, authorization by the Zentrale Auslands- und Fachvermittlung (ZAV; English: International Placement Services) that is involved in the visa process would usually be required for issuing the visa. The ZAV may grant an employment permit even prior to the request in the visa process, if the employer provides the information necessary for examination of the case beforehand. If the visa is issued, it includes permission to work in Germany. Where self-employed work is concerned – like in the example – approval by the ZAV is not necessary. 

The guest performances in the UK, Ireland, and Switzerland mentioned in the above example are subject to national regulations for entry, stay, and economic activity. Since additional resident titles and work permits may be needed there, the Indian dancer must contact the diplomatic representations of the other countries in due time to discuss the respective requirements. 

Following entry into the Federal Republic of Germany, the visa is converted by the relevant local foreigners’ registration office into a residence title with a longer validity period. After entering Germany on his/her D visa, the Indian dancer must apply for conversion of the visa into a residence permit at the relevant foreigners’ registration office.

• Due to the possibly necessary involvement of the foreigners’ registration office or ZAV, issuance of a national visa on short notice is usually not possible. A period of at least six weeks should be scheduled for the visa process. The processing time may be longer, depending on the scope of the checks required in the individual cases. This should be factored into any travel plans. 
  
  
• The nature and extent of the supporting documents may vary depending on the applicant’s country of origin or the category of the requested visa. It is therefore absolutely essential to gather all necessary information pertaining to the procedure and required documents prior to submitting an application. Information is available in brochures that can be downloaded from the websites of the German diplomatic missions.  
  
  
• A C visa that is valid for a short stay cannot be converted into a residence permit after arrival in Germany. A D visa must be applied for if the applicant intends a longer stay. 
  
  
• In light of the aspect of employment, for stays in other countries – even stays in other Schengen countries – the diplomatic missions in the host countries must be contacted to check which additional special permits may be required, if any. 
  
  
• Under Article 25 of the EU Visa Code, a visa of limited territorial validity may be granted in exceptional cases. This is also possible if the conditions of entry set out in the Schengen Borders Code (e.g., valid passport) are not met, if the Member State in question considers it necessary "on humanitarian grounds, for reasons of national interest or because of international obligations." Furthermore, a visa of this kind may be used as the basis for re-issuing a visa to an applicant within a six-month period, even if the person concerned has already used a visa for a three-month stay.
  
  Important: A visa with limited territorial validity may only be used to travel within the territory of the issuing Member State. The visa is only valid in other Member States in special cases, provided they have agreed to this.
  
  

The following are the minimum requirements for a visa application:

• a fully completed application form signed by the applicant  
  
  
• a passport photo in line with the criteria of the Visa Code (color, 35 x 45 mm, light background, etc.)
  
  
• a valid and approved passport  
  
  
• documentation of independent or third-party funding (e.g., letter of intent of the inviting party)  
  
  
• health insurance valid throughout the entire Schengen area, which also covers stays for employment purposes, if necessary (see Insurances)
  
  
• depending on the type of visa, possibly other evidence such as invitation letters, service contracts, airplane ticket receipts, memberships in artists’ associations, marriage certificates, birth certificates of children, certificates of land ownership and other evidence documenting the intent of the applicant to return to his/her country of origin.

In cases where the applicant does not have sufficient financial resources, a third party can commit to cover the costs arising during the stay of the guest in Germany (including the costs of any medical treatment and transport back to the country of origin) by providing a letter of intent/formal obligation in line with §§ 66-68 AufenthG (English: Residence Act) (sample letter of intent - please do not use!). 

Domestically, the foreigners’ registration office at the place of residence of the party submitting the letter of intent/formal obligation is responsible for receiving the letter of intent/formal obligation; abroad, this task is handled by the diplomatic representations.  

A letter of intent/formal obligation only fulfills the requirement of securing the guest’s livelihood if the person submitting it is able to pay. Sufficient evidence must be provided if the foreigners’ registration office does not know whether he or she can cover the amount. The competent authority carries out a credit check based on the information provided by the person submitting the letter. 

In  special cases (for example if the inviter can be found in Part B of the commercial registry, i.e. corporations such as limited liability companies or UG (Unternehmergesellschaft; English: entrepreneurial company), the letter of intent/formal obligation may be submitted on a non-official form. 

On its website, the city of Cologne provides a guide for preparing an application for issuance of a formal obligation (in German language).

The respective guide for Berlin (also in German) can be found here.

Detailed information of the Federal Ministry of the Interior on letters of intent (German).