By comparison with the full-size 743-page Ortografía de la lengua española, this basic orthography manual looks tiny, but it should be ideal for the vast majority of users.
At first, I thought this tiny-looking "Ortografía básica de la lengua española" (ISBN 978-607-07-1069-8) would be superficial. It isn't superficial. And it isn't really tiny either.
Like the RAE grammar books, this is an efficiently written specification, like the best communications engineering and computer language specifications.
In the preliminary pages xv-xvii, they state that they are using their own phonetic alphabet for this book, rather than the international standard IPA or the Spanish-specific RFE. They give a side-by-side table so that you can cross-reference if you know the IPA or RFE already. Their choice of phonetic alphabet is essentially identical to standard Madrid pronunciation.
In Chapter 1 (pages 1-35) "Uso de las letras", they very briefly discuss "el seseo y el ceceo" and "el yeísmo", and some of the fine points of these issues. Then they present the names of the letters of the alphabet, and the use of the digraphs ch, ll, gu, qu and rr. Then some fine points regarding pronunciation of vowels. Then some notes about how consonants are written, pointing out that some consonants may be written in multiple ways, including special issues regarding the letters "h" and "x". Then they discuss doubled vowels and consonant-groups, both initial and medial. Most of this is fairly familiar from the first chapter of any good Spanish grammar tutorial, but it's good to see it all written out here in full, much more systematically than in the typical grammar tutorial which assumes that a teacher will fill in the gaps.
It is sometimes not quite clear whether the book is talking about orthography (how to write words which you know how to pronounce) or pronunciation (how to pronounce words which you know how to write). I guess they're too closely connected to separate.
Chapter 2 (pages 36-58), "Uso de la tilde", explains the use of the tilde to indicate accents ("Función prosódica"), or to distinguish otherwise identically written words ("Función diacrítica"). They give the familiar rules for indicating accents, particularly for diphthongs, triphthongs and hiatus. Pages 44-56 describe the tricky diacritic function, which apparently even native speakers regularly ignore. Then they discuss accents for compound words and some other special cases.
Chapter 3 (pages 59-110) "Uso de los signos ortográficos" deals with punctuation, including pretty much every punctuation issue, including how to write abbreviated dates. I am very glad that they point out various wrong uses of an apostrophe, such as "los 30's" and "DVD's".
Chapter 4 (pages 111-133) "Uso de las mayúsculas" gives detailed guidelines for when to use capital letters and when you should not, including when to use block capitals, and how to write abbreviations with mixed upper and lower case.
Chapter 5 (pages 134-146) "Unión y separación de palabras y otros elementos en la escritura" describes when to separate compound words and when to join them, and how accent is affected by this. Also described are various rules for prefixes, like "super-8", "pre-1945" or "pro-Obama".
Chapter 6 (pages 147-157) "Abreviaciones gráficas y símbolos" covers various issues to do with abbreviations, such as how titles like Prof. are changed from masculine to feminine. Also discussed are symbols from physics, chemistry, mathematics, engineering etc.
Chapter 7 (pages 158-195) "Ortografía de expresiones que plantean dificultades específicas" discusses specific issues like words imported from other languages, how to quote text in-line from other languages, how to add accent-tildes to foreign words, how to write personal names (including the issues of baptismal and family names), how to write Latin numbers, how to write cardinal and ordinal numbers out in full words, how to write time of day and dates, and finally how to write percentages.
So they've covered a huge amount in this tiny 182 gram (6.4 oz) book. My only complaint is that the reverse-side printing shows through the thin pages, which are yellowish in colour. (The ISBN on the back cover indicates that my copy was printed in México.)
PS. 2013-1-21. I have added a "customer image" to show how small the Ortografía Básica looks by comparison with the full Ortografía and the three different sizes of the RAE Nueva Gramática. It really does look tiny by comparison!