Orthographic transcriptions of speech are important in most fields of research concerned with spoken language. For spontaneous speech they have to be created manually, resulting potentially in inconsistent or erroneous transcriptions. We propose a new flexible and easy-to-use formal language for the orthographic transcription of spontaneous speech. All relevant phenomena introduced by spontaneous spoken dialogues are covered. The transcription serves as a meta-language from which various representations for different research purposes can be generated automatically.