Tinyseq is an XML based format for plain sequences. Details are available in the NCBI documentation.
<?xml version="1.0"?>
<!DOCTYPE TSeqSet PUBLIC "-//NCBI//NCBI TSeq/EN" http://www.ncbi.nlm.nih.gov/dtd/NCBI_TSeq.dtd>
<TSeqSet>
<TSeq>
<TSeq_seqtype value="nucleotide"/>
<TSeq_gi>`11321596`</TSeq_gi>
<TSeq_sid>`ref|NM_002253.1|`</TSeq_sid>
<TSeq_taxid>`9606`</TSeq_taxid>
<TSeq_orgname>`Homo sapiens`</TSeq_orgname>
<TSeq_defline>`Homo sapiens kinase insert domain receptor, mRNA`</TSeq_defline>
<TSeq_length>`58`</TSeq_length>
<TSeq_sequence>`ACTGAGTCCCGGGACCCCGGGAGAGCGGTCAGTGTGTGGTCGCTGCGTTTT`</TSeq_sequence>
</TSeq>
</TSeqSet>