1. High-Tech Readers
These are experts in the field being written about, your peers, and people who work in a similar job but at a different company. You would not need to include background as experts would know what the purpose of the document is. Detailed descriptions are not required, nor would you need to include explanations and definitions.
2. Low-Tech Readers
This audience includes subordinates, co-workers from a different department, and colleagues who are unfamiliar with equipment or procedures. Bosses who have not worked with the new technology may also be included. They will require more substantial details as well as definitions of abbreviations, acronyms and unfamiliar terms. Since this audience is not familiar with your field of expertise, you will need to include some background information. Why you are writing this document, what you hope to accomplish with it, and some past history.
3. Lay-Persons
This audience has no knowledge about your field of expertise and will need background information, extensive details and explanations. Abbreviations and acronyms will need definitions. Avoid high-tech terms or define them thoroughly. Write concisely and with clarity. Use simple graphics wherever necessary.
4. Multiple Audience
This audience includes the high-tech, low-tech and lay people. You will basically writing in low-tech mode but will need to include a separate background page and a glossary that the high-tech and some low-tech people can skip, but that the lay people will find useful and even necessary in order to understand what you are trying to convey with your document.