What does ISBP cover?

ISBP consists of 200 paragraphs, grouped around headings such as "Title of documents and combined documents", "Amounts", "Misspellings and typing errors" and so on.

Some examples:
Misspellings and typographical errors.  The letter of credit calls for "milling machines", but the commercial invoice refers to "milling mashines".  Paragraph 28 says that this is not a discrepancy, provided that the meaning is not affected
Titles of documents. If the letter of credit calls for a packing list, does the document provided have to bear the title "Packing list"?

Paragraph 43 says not. If a document is supplied that fulfils the function of a packing list, then there is no discrepancy.  And Paragraph 44 says that it is acceptable to combine two required documents into a single document, such as a combined Packing and Weight list
Use of abbreviations. The letter of credit describes the beneficiary as Mantissa Limited, but documents refer to Mantissa Ltd. Paragraph 6 says this is not a discrepancy, and nor is the use of generally accepted abbreviations for weights and measures
Other topics discussed include:
Which documents MUST be dated and signed, irrespective of any instructions on the LC?
In what languages may documents be presented? Can an Advising bank control or limit the languages to be used?
What constitutes an "original document"?
What clausing on a bill of lading makes it no longer 'clean'?

Paragraphs 22 and 23 deal with terms such as "stale documents", "shipping documents" and "as soon as possible", which may appear in credits, but which are undefined within UCP. Definitions are given for the first two of these; but for the last, the recommendation is that the phrase should never be used and banks can ignore it.

In addition to the quite prescriptive recommendations listed above, ISBP also contains some general guidance on good practice.  

For example, paragraph 2 says that issuing banks have the right to "supplement or develop" the instructions given by the applicant, so that the letter of credit is unambiguous and workable, and paragraph 4 strongly deprecates credits which require documents that must be issued or countersigned by the applicant.