Question: What does the Hacker-Pschorr Brewery have to limit in order to comply with German regulations?

Context paragraphs:
Hacker-Pschorr Brewery: Hacker-Pschorr is a brewery in Munich, formed in 1972 out of the merger of two breweries, Hacker and Pschorr.  Hacker was founded in 1417, 99 years before the enactment of the Reinheitsgebot Purity Law of 1516.

Reinheitsgebot: The Reinheitsgebot (] , literally "purity order"), sometimes called the "German Beer Purity Law" in English, is the collective name for a series of regulations limiting the ingredients in beer in Germany and the states of the former Holy Roman Empire.  The best-known version of the law was adopted in Bavaria in 1516, but similar regulations predate the Bavarian order, and modern regulations also significantly differ from the 1516 Bavarian version.

KAGG (law): Gesetz über Kapitalanlagegesellschaften (KAGG) — (German for Investment Company Act) — was a set of German regulations for Mutual Funds that was phased out in 2007 and replaced by the German Investment Modernization Act ("Investement Act").  An objective of the new Investment Act is to promote Germany as an investment fund market, stemming the erstwhile exodus of German-managed funds that became domiciled in other European havens, namely Luxembourg.  BaFin is the regulatory enforcement agency that oversees the German financial industry.

Building regulations approval: To comply with the Building Act 1984 and the subsequent statutory instruments known as the Building Regulations, Building regulations approval is required to construct certain structures in England and Wales.  Construction projects falling into this category are sometimes referred to as "notifiable", however this is different from the "notification" (which may also be required under the Construction (Design and Management) Regulations 2015, which seeks to monitor health and safety in construction projects.

Self-executing order: A self-executing order is a type of court order.  Court orders are usually made with only immediate effect, and without any future effect.  With a self-executing order, an order is made by a court that a party to a legal matter must comply with a request by a future date or be subject to legal sanctions.  If the party does not comply with the request, the sanctions will apply with no further court order required.

Comply or explain: Comply or explain is a regulatory approach used in the United Kingdom, Germany, the Netherlands and other countries in the field of corporate governance and financial supervision.  Rather than setting out binding laws, government regulators (in the UK, the Financial Reporting Council, in Germany, under the Aktiengesetz) set out a code, which listed companies may either comply with, or if they do not comply, explain publicly why they do not.  The UK Corporate Governance Code, the German Corporate Governance Code (or Deutscher Corporate Governance Kodex) and the Dutch Corporate Governance Code 'Code Tabaksblat' () use this approach in setting minimum standards for companies in their audit committees, remuneration committees and recommendations for how good companies should divide authority on their boards.

Mercedes-Benz short bonnet trucks: The Mercedes-Benz "Kurzhauber" (short-bonnet) truck is a conventional layout, cab-after-engine truck manufactured from 1959 to 1995.  In Germany it is most commonly referred to as the "Kurzhauber" (for "short bonnet").  The engine intruded into the cabin underneath the windshield, all in the name of making a shorter truck to meet the strict period German regulations on overall length.

Title 47 CFR Part 15: Code of Federal Regulations, Title 47, Part 15 (47 CFR 15) is an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions.  It is a part of Title 47 of the Code of Federal Regulations (CFR), and regulates everything from spurious emissions to unlicensed low-power broadcasting.  Nearly every electronics device sold inside the United States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.

Corporate social responsibility: Corporate social responsibility (CSR, also called corporate conscience, corporate citizenship or responsible business) is a form of corporate self-regulation integrated into a business model.  CSR policy functions as a self-regulatory mechanism whereby a business monitors and ensures its active compliance with the spirit of the law, ethical standards and national or international norms. With some models, a firm's implementation of CSR goes beyond compliance and statutory requirements, which engages in "actions that appear to further some social good, beyond the interests of the firm and that which is required by law".  The binary choice between 'complying' with the law and 'going beyond' the law must be qualified with some nuance.  In many areas such as environmental or labor regulations, employers can choose to comply with the law, to go beyond the law, but they can also choose to not comply with the law, such as when they deliberately ignore gender equality or the mandate to hire disabled workers.  There must be a recognition that many so-called 'hard' laws are also 'weak' laws, weak in the sense that they are poorly enforced, with no or little control or no or few sanctions in case of non-compliance.  'Weak' law must not be confused with soft law.  The aim is to increase long-term profits and shareholder trust through positive public relations and high ethical standards to reduce business and legal risk by taking responsibility for corporate actions.  CSR strategies encourage the company to make a positive impact on the environment and stakeholders including consumers, employees, investors, communities, and others.

Greisen–Zatsepin–Kuzmin limit: The Greisen–Zatsepin–Kuzmin limit (GZK limit) is a theoretical upper limit on the energy of cosmic rays (high energy charged particles from space) coming from "distant" sources.  The limit is , or about 8 joules.  The limit is set by slowing-interactions of cosmic ray protons with the microwave background radiation over long distances (~160 million light-years).  The limit is at the same order of magnitude as the upper limit for energy at which cosmic rays have experimentally been detected.  For example, one extreme-energy cosmic ray has been detected which appeared to possess a record (50 joules) of energy (about the same as the kinetic energy of a 60 mph baseball).

Supporting paragraphs: Hacker-Pschorr Brewery Reinheitsgebot
Answer: ingredients in beer