diff --git a/doc/sBasic.pdf b/doc/sBasic.pdf
new file mode 100644
index 0000000..90e1fca
--- /dev/null
+++ b/doc/sBasic.pdf
@@ -0,0 +1,825 @@
+%PDF-1.4
+%“Œ‹ž ReportLab Generated PDF document http://www.reportlab.com
+1 0 obj
+<< /F1 2 0 R /F2 3 0 R /F3 26 0 R >>
+endobj
+2 0 obj
+<< /BaseFont /Helvetica /Encoding /WinAnsiEncoding /Name /F1 /Subtype /Type1 /Type /Font >>
+endobj
+3 0 obj
+<< /BaseFont /Helvetica-Bold /Encoding /WinAnsiEncoding /Name /F2 /Subtype /Type1 /Type /Font >>
+endobj
+4 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 468.0236 0 ] /Rect [ 62.69291 663.0236 127.7229 675.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+5 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 468.0236 0 ] /Rect [ 527.0227 663.7736 532.5827 675.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+6 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 375.0236 0 ] /Rect [ 62.69291 645.0236 209.9629 657.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+7 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 375.0236 0 ] /Rect [ 527.0227 645.7736 532.5827 657.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+8 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 342.0236 0 ] /Rect [ 62.69291 627.0236 118.2629 639.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+9 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 342.0236 0 ] /Rect [ 527.0227 627.7736 532.5827 639.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+10 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 231.0236 0 ] /Rect [ 82.69291 609.0236 242.7529 621.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+11 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 27 0 R /XYZ 62.69291 231.0236 0 ] /Rect [ 527.0227 609.7736 532.5827 621.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+12 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 28 0 R /XYZ 62.69291 552.6236 0 ] /Rect [ 82.69291 591.0236 186.0729 603.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+13 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 28 0 R /XYZ 62.69291 552.6236 0 ] /Rect [ 527.0227 591.7736 532.5827 603.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+14 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 28 0 R /XYZ 62.69291 387.4236 0 ] /Rect [ 82.69291 573.0236 109.9329 585.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+15 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 28 0 R /XYZ 62.69291 387.4236 0 ] /Rect [ 527.0227 573.7736 532.5827 585.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+16 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 28 0 R /XYZ 62.69291 258.2236 0 ] /Rect [ 82.69291 555.0236 122.1529 567.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+17 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 28 0 R /XYZ 62.69291 258.2236 0 ] /Rect [ 527.0227 555.7736 532.5827 567.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+18 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 620.6236 0 ] /Rect [ 82.69291 537.0236 169.3829 549.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+19 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 620.6236 0 ] /Rect [ 527.0227 537.7736 532.5827 549.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+20 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 519.4236 0 ] /Rect [ 82.69291 519.0236 131.0329 531.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+21 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 519.4236 0 ] /Rect [ 527.0227 519.7736 532.5827 531.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+22 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 459.4236 0 ] /Rect [ 82.69291 501.0236 113.8129 513.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+23 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 459.4236 0 ] /Rect [ 527.0227 501.7736 532.5827 513.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+24 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 339.4236 0 ] /Rect [ 62.69291 483.0236 208.2929 495.0236 ] /Subtype /Link /Type /Annot >>
+endobj
+25 0 obj
+<< /Border [ 0 0 0 ] /Contents () /Dest [ 29 0 R /XYZ 62.69291 339.4236 0 ] /Rect [ 527.0227 483.7736 532.5827 495.7736 ] /Subtype /Link /Type /Annot >>
+endobj
+26 0 obj
+<< /BaseFont /Courier /Encoding /WinAnsiEncoding /Name /F3 /Subtype /Type1 /Type /Font >>
+endobj
+27 0 obj
+<< /Annots [ 4 0 R 5 0 R 6 0 R 7 0 R 8 0 R 9 0 R 10 0 R 11 0 R 12 0 R 13 0 R 
+  14 0 R 15 0 R 16 0 R 17 0 R 18 0 R 19 0 R 20 0 R 21 0 R 22 0 R 23 0 R 
+  24 0 R 25 0 R ] /Contents 45 0 R /MediaBox [ 0 0 595.2756 841.8898 ] /Parent 44 0 R /Resources << /Font 1 0 R /ProcSet [ /PDF /Text /ImageB /ImageC /ImageI ] >> /Rotate 0 
+  /Trans <<  >> /Type /Page >>
+endobj
+28 0 obj
+<< /Contents 46 0 R /MediaBox [ 0 0 595.2756 841.8898 ] /Parent 44 0 R /Resources << /Font 1 0 R /ProcSet [ /PDF /Text /ImageB /ImageC /ImageI ] >> /Rotate 0 /Trans <<  >> 
+  /Type /Page >>
+endobj
+29 0 obj
+<< /Contents 47 0 R /MediaBox [ 0 0 595.2756 841.8898 ] /Parent 44 0 R /Resources << /Font 1 0 R /ProcSet [ /PDF /Text /ImageB /ImageC /ImageI ] >> /Rotate 0 /Trans <<  >> 
+  /Type /Page >>
+endobj
+30 0 obj
+<< /Outlines 32 0 R /PageLabels 48 0 R /PageMode /UseNone /Pages 44 0 R /Type /Catalog >>
+endobj
+31 0 obj
+<< /Author () /CreationDate (D:20181002080507+00'00') /Creator (\(unspecified\)) /Keywords () /ModDate (D:20181002080507+00'00') /Producer (ReportLab PDF Library - www.reportlab.com) 
+  /Subject (\(unspecified\)) /Title (sBasic -- yet another simple programming language) /Trapped /False >>
+endobj
+32 0 obj
+<< /Count 12 /First 33 0 R /Last 43 0 R /Type /Outlines >>
+endobj
+33 0 obj
+<< /Dest [ 27 0 R /XYZ 62.69291 468.0236 0 ] /Next 34 0 R /Parent 32 0 R /Title (sBasic Usage) >>
+endobj
+34 0 obj
+<< /Dest [ 27 0 R /XYZ 62.69291 375.0236 0 ] /Next 35 0 R /Parent 32 0 R /Prev 33 0 R /Title (sBasic Language Specification) >>
+endobj
+35 0 obj
+<< /Count 7 /Dest [ 27 0 R /XYZ 62.69291 342.0236 0 ] /First 36 0 R /Last 42 0 R /Next 43 0 R /Parent 32 0 R 
+  /Prev 34 0 R /Title (Whitespace) >>
+endobj
+36 0 obj
+<< /Dest [ 27 0 R /XYZ 62.69291 231.0236 0 ] /Next 37 0 R /Parent 35 0 R /Title (Variables and Arithmetic Operations) >>
+endobj
+37 0 obj
+<< /Dest [ 28 0 R /XYZ 62.69291 552.6236 0 ] /Next 38 0 R /Parent 35 0 R /Prev 36 0 R /Title (Conditional Statements) >>
+endobj
+38 0 obj
+<< /Dest [ 28 0 R /XYZ 62.69291 387.4236 0 ] /Next 39 0 R /Parent 35 0 R /Prev 37 0 R /Title (Loops) >>
+endobj
+39 0 obj
+<< /Dest [ 28 0 R /XYZ 62.69291 258.2236 0 ] /Next 40 0 R /Parent 35 0 R /Prev 38 0 R /Title (Routines) >>
+endobj
+40 0 obj
+<< /Dest [ 29 0 R /XYZ 62.69291 620.6236 0 ] /Next 41 0 R /Parent 35 0 R /Prev 39 0 R /Title (Special Commands) >>
+endobj
+41 0 obj
+<< /Dest [ 29 0 R /XYZ 62.69291 519.4236 0 ] /Next 42 0 R /Parent 35 0 R /Prev 40 0 R /Title (Comments) >>
+endobj
+42 0 obj
+<< /Dest [ 29 0 R /XYZ 62.69291 459.4236 0 ] /Parent 35 0 R /Prev 41 0 R /Title (Strings) >>
+endobj
+43 0 obj
+<< /Dest [ 29 0 R /XYZ 62.69291 339.4236 0 ] /Parent 32 0 R /Prev 35 0 R /Title (sBasic Application Extensions) >>
+endobj
+44 0 obj
+<< /Count 3 /Kids [ 27 0 R 28 0 R 29 0 R ] /Type /Pages >>
+endobj
+45 0 obj
+<< /Length 5969 >>
+stream
+1 0 0 1 0 0 cm  BT /F1 12 Tf 14.4 TL ET
+q
+1 0 0 1 62.69291 717.0236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 28 Tm /F2 20 Tf 24 TL 34.89488 0 Td (sBasic -- yet another simple programming) Tj T* 156.15 0 Td (language) Tj T* -191.0449 0 Td ET
+Q
+Q
+q
+1 0 0 1 62.69291 684.0236 cm
+q
+BT 1 0 0 1 0 3.5 Tm 21 TL /F2 17.5 Tf 0 0 0 rg (Contents) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 480.0236 cm
+0 0 0 rg
+BT /F1 10 Tf 12 TL ET
+q
+1 0 0 1 0 183 cm
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F2 10 Tf 0 0 .501961 rg (sBasic Usage) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 183 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F2 10 Tf 12 TL 66.44 0 Td (1) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 165 cm
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F2 10 Tf 0 0 .501961 rg (sBasic Language Specification) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 165 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F2 10 Tf 12 TL 66.44 0 Td (1) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 147 cm
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F2 10 Tf 0 0 .501961 rg (Whitespace) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 147 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F2 10 Tf 12 TL 66.44 0 Td (1) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 129 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Variables and Arithmetic Operations) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 129 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (1) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 111 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Conditional Statements) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 111 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (2) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 93 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Loops) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 93 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (2) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 75 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Routines) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 75 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (2) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 57 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Special Commands) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 57 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (3) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 39 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Comments) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 39 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (3) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 21 cm
+q
+BT 1 0 0 1 20 2 Tm 12 TL /F1 10 Tf 0 0 .501961 rg (Strings) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 21 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL 66.44 0 Td (3) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+1 0 0 1 0 3 cm
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F2 10 Tf 0 0 .501961 rg (sBasic Application Extensions) Tj T* ET
+Q
+Q
+q
+1 0 0 1 397.8898 3 cm
+q
+0 0 .501961 rg
+0 0 .501961 RG
+BT 1 0 0 1 0 2 Tm /F2 10 Tf 12 TL 66.44 0 Td (3) Tj T* -66.44 0 Td ET
+Q
+Q
+q
+Q
+Q
+q
+1 0 0 1 62.69291 447.0236 cm
+q
+BT 1 0 0 1 0 3.5 Tm 21 TL /F2 17.5 Tf 0 0 0 rg (sBasic Usage) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 417.0236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 14 Tm /F1 10 Tf 12 TL .616905 Tw (sBasic is designed for freely programmable embedded applications that do not allow scripting languages) Tj T* 0 Tw (like JS, Lua or Python.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 387.0236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 14 Tm /F1 10 Tf 12 TL .571751 Tw (One should not write applications with it, in contrary it is designed to write extensions for micro controller) Tj T* 0 Tw (projects.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 354.0236 cm
+q
+BT 1 0 0 1 0 3.5 Tm 21 TL /F2 17.5 Tf 0 0 0 rg (sBasic Language Specification) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 321.0236 cm
+q
+BT 1 0 0 1 0 3.5 Tm 21 TL /F2 17.5 Tf 0 0 0 rg (Whitespace) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 291.0236 cm
+q
+BT 1 0 0 1 0 14 Tm 2.394269 Tw 12 TL /F1 10 Tf 0 0 0 rg (The following whitespace characters will be converted to a single blank \() Tj /F3 10 Tf 0 0 0 rg (0x20) Tj /F1 10 Tf 0 0 0 rg (\): ) Tj /F3 10 Tf 0 0 0 rg (\\t\\r ) Tj /F1 10 Tf 0 0 0 rg (and multiple) Tj T* 0 Tw (blanks.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 261.0236 cm
+q
+BT 1 0 0 1 0 14 Tm .59284 Tw 12 TL /F1 10 Tf 0 0 0 rg (The newline character \() Tj /F3 10 Tf 0 0 0 rg (\\n) Tj /F1 10 Tf 0 0 0 rg (\) is a special character however multiple newline characters will be interpreted) Tj T* 0 Tw (as one.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 243.0236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (A statement always ends with a newline character. Tokens are separated by blanks.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 213.0236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Variables and Arithmetic Operations) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 183.0236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 14 Tm /F1 10 Tf 12 TL 1.831318 Tw (Variables have data types. Usually they will be integers, but there might be other application specific) Tj T* 0 Tw (datatypes.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 165.0236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (Variables have to be declared explicitly using the scheme:) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 131.8236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 24 re B*
+Q
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F3 10 Tf 0 0 0 rg (<) Tj (datatype) Tj (>) Tj ( ) Tj (<) Tj (variablename) Tj (>) Tj ( '=' ) Tj (<) Tj (value) Tj (>) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 99.82362 cm
+q
+BT 1 0 0 1 0 14 Tm 1.016651 Tw 12 TL /F2 10 Tf 0 0 0 rg (Note ) Tj /F1 10 Tf (that variable names must start with an alphabetic character. Variable names can contain after the) Tj T* 0 Tw (first character all of the following characters:) Tj T* ET
+Q
+Q
+ 
+endstream
+endobj
+46 0 obj
+<< /Length 4567 >>
+stream
+1 0 0 1 0 0 cm  BT /F1 12 Tf 14.4 TL ET
+q
+1 0 0 1 62.69291 739.8236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 24 re B*
+Q
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F3 10 Tf 12 TL (a..zA..Z0..9_) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 719.8236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (Datatype names must follow the same conventions as the variable name convention.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 701.8236 cm
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F2 10 Tf 0 0 0 rg (Note) Tj /F1 10 Tf (: Variables are always global.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 683.8236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (Here is an example for valid variable declarations:) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 626.6236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 48 re B*
+Q
+q
+0 0 0 rg
+BT 1 0 0 1 0 26 Tm /F3 10 Tf 12 TL (int A = 2) Tj T* (int B = 3) Tj T* (int A_plus_B = 0) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 594.6236 cm
+q
+BT 1 0 0 1 0 14 Tm 2.466412 Tw 12 TL /F1 10 Tf 0 0 0 rg (Arithmetic commands are application specific, for integer usually ) Tj /F3 10 Tf 0 0 0 rg (+) Tj ( ) Tj (-) Tj ( ) Tj (*) Tj ( ) Tj (/ ) Tj /F1 10 Tf 0 0 0 rg (are defined. Arithmetic) Tj T* 0 Tw (commands can be grouped by using parenthesis ) Tj /F3 10 Tf 0 0 0 rg (\(\)) Tj /F1 10 Tf 0 0 0 rg (.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 564.6236 cm
+q
+BT 1 0 0 1 0 14 Tm .515988 Tw 12 TL /F3 10 Tf 0 0 0 rg (* ) Tj /F1 10 Tf 0 0 0 rg (and ) Tj /F3 10 Tf 0 0 0 rg (/ ) Tj /F1 10 Tf 0 0 0 rg (will be executed before ) Tj /F3 10 Tf 0 0 0 rg (+ ) Tj /F1 10 Tf 0 0 0 rg (and ) Tj /F3 10 Tf 0 0 0 rg (-) Tj /F1 10 Tf 0 0 0 rg (, the inner of parenthesis will be executed before the outer and) Tj T* 0 Tw (by default commands will be executed in the order they appear.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 534.6236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Conditional Statements) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 516.6236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (sBasic knows the if-else-structure:) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 399.4236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 108 re B*
+Q
+q
+BT 1 0 0 1 0 86 Tm 12 TL /F3 10 Tf 0 0 0 rg (IF ) Tj (<) Tj (expr) Tj (>) Tj  T* (THEN) Tj T* (        ) Tj (<) Tj (statement) Tj (>) Tj  T* (        {) Tj (<) Tj (statement) Tj (>) Tj (}) Tj T* ([ELSE) Tj T* (        ) Tj (<) Tj (statement) Tj (>) Tj  T* (        {) Tj (<) Tj (statement) Tj (>) Tj (}]) Tj T* (FI) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 369.4236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Loops) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 351.4236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (sBasic knows the while-loop:) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 270.2236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 72 re B*
+Q
+q
+BT 1 0 0 1 0 50 Tm 12 TL /F3 10 Tf 0 0 0 rg (WHILE ) Tj (<) Tj (expr) Tj (>) Tj  T* (DO) Tj T* (        ) Tj (<) Tj (statement) Tj (>) Tj  T* (        {) Tj (<) Tj (statement) Tj (>) Tj (}) Tj T* (DONE) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 240.2236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Routines) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 210.2236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 14 Tm /F1 10 Tf 12 TL .012927 Tw (Because in sBasic variables are always global there is no need for functions. Instead Routines are used to) Tj T* 0 Tw (group code.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 168.2236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 26 Tm /F1 10 Tf 12 TL 1.907045 Tw (Routines can be defined defined at any point of the code but the first statement. However when the) Tj T* 0 Tw 1.886412 Tw (program execution reaches a Routine this will result in a stack-underflow. The compiler will therefore) Tj T* 0 Tw (check that a routine cannot be reached without a call.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 138.2236 cm
+q
+BT 1 0 0 1 0 14 Tm 2.499398 Tw 12 TL /F1 10 Tf 0 0 0 rg (Any routine must therefore not be the first statement and must follow either a ) Tj /F3 10 Tf 0 0 0 rg (CALL ) Tj /F1 10 Tf 0 0 0 rg (or the ) Tj /F3 10 Tf 0 0 0 rg (HALT) Tj T* 0 Tw /F1 10 Tf 0 0 0 rg (command.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 120.2236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (A routine is defined like this:) Tj T* ET
+Q
+Q
+ 
+endstream
+endobj
+47 0 obj
+<< /Length 4211 >>
+stream
+1 0 0 1 0 0 cm  BT /F1 12 Tf 14.4 TL ET
+q
+1 0 0 1 62.69291 703.8236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 60 re B*
+Q
+q
+BT 1 0 0 1 0 38 Tm 12 TL /F3 10 Tf 0 0 0 rg (ROUTINE ) Tj (<) Tj (routine_name) Tj (>) Tj  T* (        ) Tj (<) Tj (statement) Tj (>) Tj  T* (        {) Tj (<) Tj (statement) Tj (>) Tj (}) Tj T* (END) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 683.8236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (The name of a Routine must follow the conventions for variable names.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 665.8236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (Routines can be executed by calling them:) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 632.6236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 24 re B*
+Q
+q
+BT 1 0 0 1 0 2 Tm 12 TL /F3 10 Tf 0 0 0 rg (CALL ) Tj (<) Tj (routine_name) Tj (>) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 602.6236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Special Commands) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 584.6236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (There is one built-in special command:) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 551.4236 cm
+q
+q
+1 0 0 1 0 0 cm
+q
+1 0 0 1 6.6 6.6 cm
+q
+.662745 .662745 .662745 RG
+.5 w
+.960784 .960784 .862745 rg
+n -6 -6 468.6898 24 re B*
+Q
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F3 10 Tf 12 TL (STOP) Tj T* ET
+Q
+Q
+Q
+Q
+Q
+q
+1 0 0 1 62.69291 531.4236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (that will cause the bytecode interpreter to halt.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 501.4236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Comments) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 471.4236 cm
+q
+BT 1 0 0 1 0 14 Tm 1.311988 Tw 12 TL /F1 10 Tf 0 0 0 rg (Comments start with a ) Tj /F3 10 Tf 0 0 0 rg (# ) Tj /F1 10 Tf 0 0 0 rg (at the beginning of the line and span over the entire line. The ) Tj /F3 10 Tf 0 0 0 rg (# ) Tj /F1 10 Tf 0 0 0 rg (sign might) Tj T* 0 Tw (follow one \(or more\) blanks.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 441.4236 cm
+q
+BT 1 0 0 1 0 3 Tm 18 TL /F2 15 Tf 0 0 0 rg (Strings) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 423.4236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 2 Tm /F1 10 Tf 12 TL (There are two types of strings in sBasic: single line strings and multi line strings.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 381.4236 cm
+q
+BT 1 0 0 1 0 26 Tm .112619 Tw 12 TL /F1 10 Tf 0 0 0 rg (A single line string starts and ends with a ) Tj /F3 10 Tf 0 0 0 rg (" ) Tj /F1 10 Tf 0 0 0 rg (character and must not span over several lines. The following) Tj T* 0 Tw .368988 Tw (conventions for strings are used: ) Tj /F3 10 Tf 0 0 0 rg (` ) Tj /F1 10 Tf 0 0 0 rg (is treated as character ) Tj /F3 10 Tf 0 0 0 rg (`) Tj /F1 10 Tf 0 0 0 rg (, ) Tj /F3 10 Tf 0 0 0 rg (\\\\ ) Tj /F1 10 Tf 0 0 0 rg (is treated as a single ) Tj /F3 10 Tf 0 0 0 rg (\\) Tj /F1 10 Tf 0 0 0 rg (, ) Tj /F3 10 Tf 0 0 0 rg (\\n,r,t ) Tj /F1 10 Tf 0 0 0 rg (is the) Tj T* 0 Tw (newline, carriage return, tab character. Any other combination of ) Tj /F3 10 Tf 0 0 0 rg (\\ ) Tj /F1 10 Tf 0 0 0 rg (and a character is a syntax error.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 351.4236 cm
+q
+BT 1 0 0 1 0 14 Tm 1.447209 Tw 12 TL /F1 10 Tf 0 0 0 rg (A multi line string starts and ends with a ) Tj /F3 10 Tf 0 0 0 rg (` ) Tj /F1 10 Tf 0 0 0 rg (character and can span over several lines. Every newline) Tj T* 0 Tw (character in the string will be treated as such. ) Tj /F3 10 Tf 0 0 0 rg (" ) Tj /F1 10 Tf 0 0 0 rg (is treated as character ) Tj /F3 10 Tf 0 0 0 rg (") Tj /F1 10 Tf 0 0 0 rg (.) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 318.4236 cm
+q
+BT 1 0 0 1 0 3.5 Tm 21 TL /F2 17.5 Tf 0 0 0 rg (sBasic Application Extensions) Tj T* ET
+Q
+Q
+q
+1 0 0 1 62.69291 276.4236 cm
+q
+0 0 0 rg
+BT 1 0 0 1 0 26 Tm /F1 10 Tf 12 TL 2.557126 Tw (When it comes to real world applications the sBasic language should be extended with Application) Tj T* 0 Tw .21784 Tw (Specific Commands \(ASC\). Those provide a way to directly access the assembly language controlling the) Tj T* 0 Tw (bytecode interpreter.) Tj T* ET
+Q
+Q
+ 
+endstream
+endobj
+48 0 obj
+<< /Nums [ 0 49 0 R 1 50 0 R 2 51 0 R ] >>
+endobj
+49 0 obj
+<< /S /D /St 1 >>
+endobj
+50 0 obj
+<< /S /D /St 2 >>
+endobj
+51 0 obj
+<< /S /D /St 3 >>
+endobj
+xref
+0 52
+0000000000 65535 f
+0000000075 00000 n
+0000000130 00000 n
+0000000240 00000 n
+0000000355 00000 n
+0000000526 00000 n
+0000000697 00000 n
+0000000868 00000 n
+0000001039 00000 n
+0000001210 00000 n
+0000001381 00000 n
+0000001553 00000 n
+0000001725 00000 n
+0000001897 00000 n
+0000002069 00000 n
+0000002241 00000 n
+0000002413 00000 n
+0000002585 00000 n
+0000002757 00000 n
+0000002929 00000 n
+0000003101 00000 n
+0000003273 00000 n
+0000003445 00000 n
+0000003617 00000 n
+0000003789 00000 n
+0000003961 00000 n
+0000004133 00000 n
+0000004242 00000 n
+0000004620 00000 n
+0000004830 00000 n
+0000005040 00000 n
+0000005149 00000 n
+0000005460 00000 n
+0000005538 00000 n
+0000005655 00000 n
+0000005802 00000 n
+0000005970 00000 n
+0000006110 00000 n
+0000006250 00000 n
+0000006373 00000 n
+0000006499 00000 n
+0000006633 00000 n
+0000006759 00000 n
+0000006871 00000 n
+0000007005 00000 n
+0000007083 00000 n
+0000013109 00000 n
+0000017733 00000 n
+0000022001 00000 n
+0000022063 00000 n
+0000022100 00000 n
+0000022137 00000 n
+trailer
+<< /ID 
+ % ReportLab generated PDF document -- digest (http://www.reportlab.com)
+ [(\371\300\304\374\242&eY\373\323\021\356\241\033"\261) (\371\300\304\374\242&eY\373\323\021\356\241\033"\261)]
+ /Info 31 0 R /Root 30 0 R /Size 52 >>
+startxref
+22174
+%%EOF
diff --git a/doc/sBasic.rst b/doc/sBasic.rst
new file mode 100644
index 0000000..1c9c04b
--- /dev/null
+++ b/doc/sBasic.rst
@@ -0,0 +1,203 @@
+sBasic -- yet another simple programming language
+*************************************************
+
+.. contents::
+
+sBasic Usage
+============
+
+sBasic is designed for freely programmable embedded
+applications that do not allow scripting languages like JS,
+Lua or Python. 
+
+One should not write applications with it, in contrary it is
+designed to write extensions for micro controller projects.
+
+sBasic Language Specification
+=============================
+
+Whitespace
+==========
+
+The following whitespace characters will be converted to
+a single blank (``0x20``): ``\t\r`` and multiple blanks.
+
+The newline character (``\n``) is a special character
+however multiple newline characters will be interpreted as
+one.
+
+A statement always ends with a newline character. Tokens are
+separated by blanks.
+
+Variables and Arithmetic Operations
+-----------------------------------
+
+Variables have data types. Usually they will be integers,
+but there might be other application specific datatypes.
+
+Variables have to be declared explicitly using the scheme::
+
+	<datatype> <variablename> '=' <value>
+
+**Note** that variable names must start with an alphabetic
+character. Variable names can contain after the first
+character all of the following characters::
+
+	a..zA..Z0..9_
+
+Datatype names must follow the same conventions as the
+variable name convention.
+
+**Note**: Variables are always global.
+
+Here is an example for valid variable declarations::
+
+	int A = 2
+	int B = 3
+	int A_plus_B = 0
+
+Arithmetic commands are application specific, for integer
+usually ``+ - * /`` are defined. Arithmetic commands can be
+grouped by using parenthesis ``()``. 
+
+``*`` and ``/`` will be executed before ``+`` and ``-``, the
+inner of parenthesis will be executed before the outer and
+by default commands will be executed in the order they
+appear.
+
+Conditional Statements
+----------------------
+
+sBasic knows the if-else-structure::
+
+	IF <expr>
+	THEN
+		<statement>
+		{<statement>}
+	[ELSE
+		<statement>
+		{<statement>}]
+	FI
+	
+
+Loops
+-----
+
+sBasic knows the while-loop::
+
+	WHILE <expr>
+	DO
+		<statement>
+		{<statement>}
+	DONE
+
+Routines
+--------
+
+Because in sBasic variables are always global there is no
+need for functions. Instead Routines are used to group code.
+
+Routines can be defined defined at any point of the code but
+the first statement.
+However when the program execution reaches a Routine this
+will result in a stack-underflow. The compiler will
+therefore check that a routine cannot be reached without
+a call.
+
+Any routine must therefore not be the first statement and
+must follow either a ``CALL`` or the ``HALT`` command.
+
+A routine is defined like this::
+
+	ROUTINE <routine_name>
+		<statement>
+		{<statement>}
+	END
+
+The name of a Routine must follow the conventions for
+variable names.
+
+Routines can be executed by calling them::
+
+	CALL <routine_name>
+
+Special Commands
+----------------
+
+There is one built-in special command::
+
+	STOP
+
+that will cause the bytecode interpreter to halt.
+
+Comments
+--------
+
+Comments start with a ``#`` at the beginning of the line and
+span over the entire line. The ``#`` sign might follow one
+(or more) blanks.
+
+Strings
+-------
+
+There are two types of strings in sBasic: single line
+strings and multi line strings.
+
+A single line string starts and ends with a ``"`` character
+and must not span over several lines. The following
+conventions for strings are used: ````` is treated as
+character `````, ``\\`` is treated as a single ``\``,
+``\n,r,t`` is the newline, carriage return, tab character.
+Any other combination of ``\`` and a character is a syntax
+error.
+
+A multi line string starts and ends with a ````` character
+and can span over several lines. Every newline character in
+the string will be treated as such. ``"`` is treated as
+character ``"``.
+The rest of the conventions follow the conventions for
+single line strings.
+
+**Note** that strings in sBasic are static and stored in the
+program memory.
+
+Datatypes
+---------
+
+- Strings are indicated by the ``str`` keyword. The variable
+  itself is a pointer to the actual string that will be
+  stored at the end of the program memory
+- Integers are indicated by the ``int`` keyword.
+- Characters are indicated by the ``chr`` keyword. Literal
+  characters are surrounded by two ``'`` characters. They
+  can contain escape sequences (``\ntr'``).
+- Floats are not supported by vanilla sBasic. They should
+  however be marked using the ``flt`` or ``dbl`` keywords.
+
+sBasic Application Extensions
+=============================
+
+When it comes to real world applications the sBasic language
+should be extended with Application Specific Commands (ASC).
+Those provide a way to directly access the assembly language
+controlling the bytecode interpreter.
+
+ASCs should typically compile to few assembly commands,
+like::
+
+	# sBasic
+	string string_part = string + 1
+	PUTCREF string_part
+	
+	; assembly
+	; string_part = string + 1
+	ld 0, string
+	ld 1, 1
+	add 0, 1
+	st 0, string_part
+
+	; PUTCREF string_part
+	ld 0, string_part
+	putcref 0
+	
+
diff --git a/s_basic/__init__.py b/s_basic/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/s_basic/code_segments/__init__.py b/s_basic/code_segments/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/s_basic/code_segments/abc.py b/s_basic/code_segments/abc.py
new file mode 100644
index 0000000..a8f68cb
--- /dev/null
+++ b/s_basic/code_segments/abc.py
@@ -0,0 +1,19 @@
+"""
+This module provides abstract code segment classes.
+"""
+
+
+from abc import ABC, abstractmethod
+
+class AbstractCodeSegment(ABC):
+	@abstractmethod
+	def parse(self):
+		pass
+
+class AbstractNestingCodeSegment(AbstractCodeSegment):
+	@abstractmethod
+	def parse_children(self):
+		pass
+	@abstractmethod
+	def parse_child(self):
+		pass
diff --git a/s_basic/code_segments/statements.py b/s_basic/code_segments/statements.py
new file mode 100644
index 0000000..72862de
--- /dev/null
+++ b/s_basic/code_segments/statements.py
@@ -0,0 +1,12 @@
+"""
+This module provides statement classes.
+"""
+
+from .abc import AbstractCodeSegment
+
+class VariableDefinitionStatement(AbstractCodeSegment):
+	def __init__(self, parsing_context):
+		self.parsing_context = parsing_context
+
+	def parse(self):
+
diff --git a/s_basic/context/__init__.py b/s_basic/context/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/s_basic/context/context.py b/s_basic/context/context.py
new file mode 100644
index 0000000..5a5e418
--- /dev/null
+++ b/s_basic/context/context.py
@@ -0,0 +1,56 @@
+"""
+This module provides the parsing context classes.
+"""
+from ..util import CharacterDevice
+
+class ParsingContext(object):
+	def __init__(self, file_, static_context):
+		self._file = CharacterDevice(file_)
+		self._static = static_context
+		self._line = 0
+		self._column = 0
+		self._last_column = 0
+
+	def getc(self):
+		res = self._file.getc()
+		if(res == "\n"):
+			self._line += 1
+			self._last_column = self._column
+			self._column = 0
+		else:
+			self._column += 1
+		return res
+	def ungetc(self, c):
+		if(c == "\n"):
+			self._column = self._last_column
+			self._line -= 1
+		else:
+			self._column -= 1
+		return self._file.ungetc(c)
+	def ungets(self, s):
+		for c in s:
+			self.ungetc(c)
+
+
+class StaticParsingContext(object):
+	def __init__(self, custom_kwd_code_segments, custom_ctx_code_segments):
+		self._kwd_code_segments = {
+			(["int", "str", "chr"], ["statement"]):  "variable_definition_segment",
+			(["STOP"], ["statement"]): "stop_command_segment",
+			(["CALL"], ["statement"]): "routine_call_segment",
+			(["("], ["expression", "int"]): "arithmetic_segment",
+			(["ROUTINE"], ["statement"]): "routine_segment",
+			(["WHILE"], ["statement"]): "while_segment",
+			(["IF"], ["statement"]): "if_segment",
+			(["\"", "`"], ["expression", "str"]): "string_definition_segment",
+			(["'"], ["expression", "chr"]): "character_definition_segment"
+
+		}
+
+		self._kwd_code_segments.update(custom_kwd_code_segments)
+
+		self._ctx_code_segments = {
+			["statement"]: "assignment_segment",
+			["expression", "int"]: "arithmetic_segment",
+
+
diff --git a/s_basic/util/__init__.py b/s_basic/util/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/s_basic/util/io.py b/s_basic/util/io.py
new file mode 100644
index 0000000..d357a3d
--- /dev/null
+++ b/s_basic/util/io.py
@@ -0,0 +1,18 @@
+"""
+This module provides utility functions and classed for I/O.
+"""
+
+
+class CharacterDevice(object):
+	def __init__(self, file_):
+		self._file = file_
+
+	def getc(self):
+		return self._file.read(1)
+	def ungetc(self, c):
+		self._file.seek(-1, 1)
+	def ungets(self, s):
+		self._file.seel(-len(s), 1)
+	def close(self):
+		return self._file.close()
+